December 10, 2025

Barrie Area to Be Buried in Up to 40 to 75 cm of Snow on Thursday as Arctic Air Fuels Dangerous Snow Squalls

December 10, 2025/ Brennen Perry

***NOTE: YOU CAN CLICK ON THE MAP TO OPEN A ZOOMABLE IMAGE***

Snowfall from the Alberta Clipper that slid through Southern Ontario earlier on Wednesday is beginning to taper off. The system has left its mark across the region with a widespread 10 to 20cm of snow in some areas, while others saw a slushy mix.

While the clipper may be done, the snowfall story is not. As the system pulls away, it ushers in a polar blast of cold air overnight on Wednesday. This air, combined with strong northwesterly winds, will kick the lake effect snow machine back into gear off Lake Huron and Georgian Bay.

Intense snow squalls across Simcoe, Huron and Perth counties throughout Thursday are likely to create dangerous conditions. Frigid wind chills paired with near-zero visibility will make travel extremely difficult and even life-threatening if you become stranded.

The Georgian Bay squall is expected to be particularly intense. A narrow corridor from Wasaga Beach through southwest Barrie, including Angus, Innisfil and into Bradford, may see the band lock in place for more than six hours. Snowfall rates could exceed 5cm per hour.

Localized totals around the Barrie area could approach 50 to 75cm in the hardest hit pocket. Some high resolution models even suggest 100cm is not completely off the table.

East of Lake Huron, activity will be persistent from Thursday morning through the evening. The lake effect here appears more spread out rather than focused on one specific pocket. The heaviest totals are expected across Huron and Perth counties, where up to 50cm is locally possible.

As of Wednesday evening, we are already seeing some activity begin ramping up off the southeast shoreline of Lake Huron and Georgian Bay. This will continue to organize after midnight into the early hours of Thursday.

By early morning, we expect the most focused squalls to target the Goderich to London corridor off Lake Huron and the Collingwood to Bradford stretch off Georgian Bay.

Keep in mind, this is a rough idea from the models, and the exact placement can shift if the wind direction changes even slightly.

**Hourly snowfall rates (cm)** - MAP FROM WEATHERBELL

By the time the morning commute begins around 6 AM, snow squall activity will intensify as the Georgian Bay band becomes extremely narrow and focused. Some model runs have it stretching from Wasaga Beach through Angus and into the Innisfil to the Newmarket area.

There remains uncertainty in how much snow the City of Barrie itself will receive. The gradient between limited snow and a huge dumping will be very tight. The south and west ends are most likely to see major impacts, although it would not take much of a shift for the band to slide directly into the city.

The Lake Huron activity will begin to spread out with moderate snowfall covering much of Huron and Perth counties, including Goderich, Wingham, Stratford and Listowel. Because the band is more diffuse, there will not be one intense pocket as we expect with the Georgian Bay squall.

**ESTIMATED WIND CHILL** - MAP FROM WEATHERBELL

A major factor with this round of squalls that makes the situation more dangerous is the very cold wind chills. When you wake up Thursday, wind chills will make it feel like the -20s. Combined with squalls at the same time, the risk to anyone stranded on the roads increases significantly.

Aside from the cold creating hazards, it will also boost snowfall rates. Colder air produces drier, fluffier snow, which allows the same amount of moisture to create a larger volume of accumulation.

Little will change heading into the late morning as the Georgian Bay squall remains locked in place near the Barrie area. The band could edge far enough north to put the city core into the bullseye. Keswick may also be brought into the heavy snow as the band wobbles.

For the Lake Huron squall, the band may briefly become more focused as a single strong line cutting through Goderich and into Stratford and Woodstock. Depending on slight track shifts, Kitchener or Hamilton could also be affected at times.

Conditions are expected to deteriorate further into the afternoon. The Georgian Bay squall appears to strengthen with hourly snowfall rates easily exceeding 5cm and possibly pushing 10cm. At this point, the most intense pocket is shown just southwest of Barrie, with Angus being hit hardest.

The Lake Huron squall will also become more organized with an impressive fetch stretching all the way toward Lake Erie and impacting Woodstock and Norfolk.

There is significant concern for the Hwy 400 corridor during the afternoon and evening commute from just south of Barrie to roughly Aurora. This section of highway will likely become snow covered with road crews struggling to keep up with extreme snowfall rates. Combined with whiteout conditions, travel in this zone should be avoided unless absolutely necessary.

As we head into the evening and just past midnight, the squalls will retreat closer to the lakeshores as winds weaken and moisture supply cuts off. This will lead to activity tapering to lake effect flurries overnight into Friday morning.

As always with snow squalls, snowfall forecasts should be taken with a large grain of salt. While models are in good agreement on placement and intensity, nothing is guaranteed as conditions need to align perfectly.

With that being said, we believe the hardest hit zone will be along the southeastern Georgian Bay shoreline from Wasaga Beach through Angus and into northern York Region. Barrie sits right on the edge but could easily end up inside the bullseye. Snowfall totals here are likely to exceed 40cm and may approach 75cm. Around Angus is where models show the strongest signal.

A tight gradient will set up with the north and east sides of Barrie, along with Keswick, Bradford and Collingwood, likely seeing 25 to 40cm of snow.

East of Lake Huron including Kincardine, Minto, Point Clark, Wingham, Listowel, Mitchell, Stratford, Exeter and Goderich, totals of 25 to 40cm are expected. Localized amounts up to 55cm are possible if a squall locks in place for several hours.

Totals of 15 to 25cm are possible for Midland and into central York Region including Newmarket and Aurora as well as Durham Region around Uxbridge. These areas will see occasional bursts of heavy snow near the edge of the main bands.

Southern Bruce and Grey counties along with Wellington County including Arthur and Oxford County may also see 15 to 25cm but totals depend on how far inland the bands extend.

Between 5 and 15cm is possible across the rest of York and Durham Region as well as northern Simcoe County including Orillia, Owen Sound, Shelburne, Fergus, Kitchener, Brantford and London. These locations sit farther from the core activity so most will see closer to 5cm with higher amounts only if a band stretches farther inland.

Less than 5cm is expected outside the snowbelt regions including Eastern Ontario, Deep Southwestern Ontario and the Golden Horseshoe.

December 09, 2025

Back-to-Back Clippers To Deliver Up to 20cm of Snow Across Southern Ontario by Wednesday

December 09, 2025/ Brennen Perry

It has certainly been feeling a lot like winter over the last few weeks across Southern Ontario as the snow continues to pile up. Several clippers and rounds of lake effect snow have already delivered a healthy start to the season.

That trend shows no signs of slowing down as we enter the second week of December.

An Alberta clipper duo is set to slide through Southern Ontario back-to-back over the coming days. The second clipper arriving on Wednesday is expected to be the stronger of the two. Current indications suggest heavy snow combined with strong wind gusts may heavily impact the Wednesday morning commute.

By the time the second clipper wraps up late Wednesday, combined snowfall totals are expected to range from 10 to 20cm across a wide swath of Central, Eastern and Southwestern Ontario. Localized totals up to 25cm cannot be ruled out, especially if there is some lake enhancement.

Lower totals are expected along the Lake Ontario and Lake Erie shorelines where temperatures may climb just enough for some rain to mix in later Wednesday morning. Around 4 to 8cm is possible for Deep Southwestern Ontario and the Golden Horseshoe.

In the wake of the clippers, we are also monitoring a potential prolonged snow squall risk beginning Wednesday evening and potentially continuing through the rest of the week and into the weekend. Snowbelt regions around Lake Huron and Georgian Bay could be dealing with significant snowfall totals. There is still uncertainty regarding the exact placement of these bands.

Things will begin to kick off late Tuesday morning into early Tuesday afternoon as precipitation from our first clipper enters from the west. Widespread light to moderate snow will spread across Southwestern Ontario, the Lake Huron shoreline and into portions of Central Ontario and the GTA.

This snow is not expected to be particularly intense, although locally heavier pockets are possible through the Bruce Peninsula and into Sudbury where lake enhancement may add extra moisture to an otherwise dry system.

Steady snow will continue throughout the afternoon on Tuesday and into the evening. The story with this first clipper will be the steadiness of the snowfall rather than the intensity. Major routes should remain drivable, but expect a slower evening commute with light snow ongoing at the time.

**TOTAL SNOWFALL (CM) FROM CLIPPER #1** - MAP FROM WEATHERBELL

This clipper will begin to wind down later in the day on Tuesday with final amounts ranging from 2 to 8cm. The heaviest pockets will be east of Lake Huron and Georgian Bay. For the rest of Southern Ontario, accumulation will fall on the lower end of that range.

However, do not let the lower totals by Tuesday evening lead you to let your guard down. Our next clipper is not far behind and will track toward Southern Ontario from the Midwest by late Tuesday evening.

Ahead of it, we may see a few hours of heavy snow squalls develop northeast of Georgian Bay and Lake Ontario. This could bring brief but heavy snow to areas like Parry Sound, Muskoka and Kingston.

Conditions will really begin to deteriorate with the second clipper as the bulk of the precipitation spreads into Southwestern Ontario and the Golden Horseshoe right at the height of the Wednesday morning commute.

Some wet snow or even rain may mix in along the Lake Ontario and Erie shorelines which could suppress totals around the GTA and Niagara region.

The key difference with this clipper compared to the one 24 hours earlier is that the snowfall will arrive in a much shorter window instead of being spread throughout the day.

Hourly snowfall rates may reach 2 to 4cm through the London to Kitchener corridor. While the intense snow will not last long, just a few hours of that kind of snowfall can add up fast.

Winds are also expected to gust up to 60 km/h which combined with heavy snowfall could produce blowing snow and significantly reduced visibility. The morning commute is likely to be heavily impacted and school bus cancellations are quite possible on Wednesday.

The heaviest snowfall rates will not last long for Southwestern Ontario and the GTA as the 1+cm per hour rates shift into Central and Eastern Ontario by late morning.

Temperatures will also rise through the late morning and early afternoon which may allow some rain to mix in around the GTA and the Lake Erie shoreline.

And yet, that is only the beginning because as the second clipper exits the region late Wednesday, the lake effect snow machine is expected to fire back up quickly by Wednesday evening.

Current data shows a focus on the London, Huron, Grey-Bruce, Collingwood and Barrie areas Wednesday night. The lake effect risk may carry into Thursday and possibly into the weekend as very cold air settles across Southern Ontario.

It remains unclear whether the wind direction will become stable enough to allow long-lasting snow squalls, but if it does, we could be looking at staggering snowfall totals by next week.

We will have a more precise breakdown of the snow squall risk closer to Thursday once high resolution model data is available to pinpoint where the bands may focus.

Turning back to the combined snowfall totals from the two clippers, we expect a wide zone stretching across much of Central and Eastern Ontario and into Southwestern Ontario east of Lake Huron to end up around 10 to 20cm. There is potential for over-performance as some recent models have trended upward showing widespread 20 to 25cm. As clippers can sometimes struggle with moisture, we have undercut that slightly to better reflect the consensus.

One area where that moisture struggle may occur is southeast of Georgian Bay, including Barrie and York Region. Models show slightly lower totals of 6 to 8cm here, so we have placed those regions in a 5 to 10cm range. This 5 to 10cm zone also extends along the Hwy 401 corridor into Deep Southwestern Ontario and into the Ottawa region.

For regions directly along the Lake Ontario and Erie shorelines like Toronto, Mississauga, Oakville, Burlington, Hamilton and St Catharines, snowfall may struggle to reach 5cm due to mixing potential and above freezing temperatures limiting accumulation.

Keep in mind that these are combined snowfall totals from both systems. Roughly 50-75 percent of the total will likely fall within a 6 hour period on Wednesday which is when conditions will be at their worst.

Additional snowfall is possible later Wednesday into Thursday with snow squall activity. Those amounts are not included in this map. A separate forecast will be issued on Wednesday for that.

December 08, 2025

Nasty Winter Storm Will Bring Mixed Bag of Precipitation, Flash Freeze Risk, and Strong Winds to Alberta Monday & Tuesday

December 08, 2025/ Alannah Campbell

***NOTE: if you click or tap on this image you can zoom it***

The forecast across Alberta for Monday and Tuesday is certainly complex. We are looking at all precipitation types; rain, snow, freezing rain and ice pellets; to be falling somewhere in the province and some places could see a combination of different kinds of precipitation. There is also a widespread risk of a flash freeze and to top it all off, wind gusts exceeding 100km/h are likely.

Before we get too ahead of ourselves, let’s start with the least complicated aspect of the forecast: the snow in Northern Alberta and through the Rockies.

Northern Alberta & The Rockies

Light snow has been falling in parts of Northern Alberta Monday morning and into the afternoon, trailing the previous round of widespread snowfall across the region. A narrow band of snow will persist through the afternoon and drop 5+cm of accumulating snow by the evening.

***The Hrdps model showing precipitation type and intensity at 5Pm MT on Monday, courtesy of WeatherBell.***

In the evening, widespread snow will move into Northern Alberta, including the Northern Rockies, from British Columbia. The snow will spread southeastward across Northern Alberta and into parts of Central Alberta during the evening and overnight hours.

The snowfall will last for up to 8 hours and it will start to taper off along the BC border shortly after midnight. This large band of snow will exit into Saskatchewan before sunrise, but scattered areas of light snow will linger through the morning across Northern Alberta.

The area that is expected to see snow throughout Monday afternoon will end up with the greatest accumulation by Tuesday afternoon. More than 15cm of fresh snow is anticipated over this area, especially in Peace River, on top of what has already fallen from the weekend. Beyond this, the rest of Northern Alberta and into parts of Central Alberta will be in the 5-15cm range and accumulations decrease moving southward. There is a slight caveat to this, which we will touch upon a bit further down.

For the Rockies, the snowfall will spread southward during the evening and overnight. Overall, 5-15cm can be expected throughout this region. The higher elevations will approach 15cm while the valleys will be closer, or possibly even below, 5cm.

Central Alberta

Things start to get messy in parts of Central Alberta as the band of snow travels southeastward into the region.

The arrival of a warm front that crossed through Central and Southern Alberta overnight Sunday has resulted in temperatures climbing to a few degrees above the freezing mark across the region. As the snow from Northern Alberta tracks southeast through the evening and overnight Monday, and encounters this warmer air above the surface, there will be a transition over to ice pellets (sleet) and freezing rain.

This is expected to start to occur to the north of Edmonton, from Whitecourt to St. Paul. Despite the surface temperatures remaining subzero in this area, there will be enough warm air aloft for the transition to ice pellets to happen and this area could see a few centimetres of ice pellets accumulating. The caveat mentioned above is that the map of snowfall totals also includes accumulation of ice pellets in this area.

precipitation types and their corresponding temperature profiles

Moving southward, the amount of warm air aloft increases and the precipitation will change to freezing rain. The area at risk of freezing rain stretches roughly from west of Drayton Valley and Rocky Mountain House to Wainwright and Provost. The northern part of this area will likely see a combination of ice pellets and freezing rain as the thickness of the warm air aloft decreases.

The freezing rain is expected to be light and only last for an hour or two, resulting in up to 1mm of ice accretion. However, this is still enough to cause some issues when travelling on untreated roads.

Timing-wise, the ice pellets and freezing rain will start to fall as early as 7pm Monday evening and continue into the overnight hours as the band of precipitation tracks towards Saskatchewan.

***The rdps model showing precipitation type and intensity at 3am MT on Tuesday, courtesy of WeatherBell.***

Southern Alberta

In Southern Alberta, as well as in portions of Central Alberta, surface temperatures hovering around zero, and slightly above, will lead to precipitation falling as rain with a bit of wet snow mixed in. The rain will be light and scattered, broken off from the main band of precipitation, throughout the region overnight and into Tuesday morning. Unfortunately, this poses a unique problem for this region.

In the early morning hours of Tuesday, a sharp cold front will start to blast southward through Central and Southern Alberta. Temperatures could plunge by up to 20°C in the span of only a few hours, resulting in a flash freeze of any rain that has fallen, as well as the snow melt from the previous day.

This flash freeze is expected to happen just in time for the morning commute for Calgary and communities to the north, so road conditions could be very poor if they aren’t treated ahead of time and maintained. The cold front will then stall around Calgary through the morning and afternoon before it continues tracking southward during the evening, bringing below freezing temperatures to the rest of Southern Alberta.

If that wasn’t enough, strong winds gusts up to, and possibly exceeding, 100km/h are possible in Southwestern Alberta overnight Monday. Luckily, these strong winds should die down by Tuesday morning.

***The hrdps model showing surface temperature at 1am MT on Tuesday, courtesy of WeatherBell.***

***The hrdps model showing surface temperature at 0am MT on Tuesday, courtesy of WeatherBell.***

All in all, this incoming system will impact most of Alberta, with each region expecting to be impacted in different ways. Road conditions will deteriorate across the province at some point over the next 24 hours so make sure to plan accordingly when travelling and stay safe.

December 04, 2025

Short Blast of Snow Behind a Cold Front Will End the Week with 5-15cm of Snow for Parts of Alberta

December 04, 2025/ Alannah Campbell

After some above-freezing temperatures and a mixed bag of precipitation on Thursday, a cold front will sweep through Central and Southern Alberta overnight Thursday. The arrival of cooler air will be accompanied by widespread snow on Friday. Accumulations of 5-10cm are expected across a swath of Northern and Central Alberta, as well as parts of Southern Alberta, by the end of the day Saturday.

Scattered flurries are likely Friday morning and into the early afternoon, but the snow will become more organized in the mid-afternoon. It will begin in the Grande Prairie area and then spread southeast during the late afternoon and evening. Accumulating snow will arrive in Edmonton just in time for the evening commute so the drive home may be slow.

In the late afternoon, snow will also cross into Southern Alberta from the Rockies and spread eastward through the evening. While snow is also expected to impact Calgary during the evening commute, the snow will be lighter and shouldn’t cause too many problems for drivers.

***The rdps model showing precipitation type and intensity at 7Pm MT on Friday, courtesy of WeatherBell.***

Steady snowfall is expected to continue across a large stretch of the province into the overnight hours, but it will start to taper off in the early morning. By sunrise on Saturday, most of the snow will have ended, but there will still be some lingering light snow throughout the remainder of the day.

Overall, 5-15cm of snow can be expected from Grande Prairie through Edmonton and towards the Saskatchewan border. Most of this area will be in the 5-10cm range, but snowfall totals could approach 15cm around the Grande Prairie and High Prairie.

In Southern Alberta, some localized intensification is possible Friday evening and overnight around Lethbridge and Taber, which would lead to accumulation exceeding 5cm. Otherwise, the remainder of Central and Southern Alberta and into Northern Alberta will see 2-5cm of snow, but there is the possibility of snowfall totals exceeding 5cm locally.

Winds should remain fairly light while the snow is falling so blowing snow shouldn’t be too much of a concern.

December 03, 2025

Brief, Intense Snow Squalls Return to Southern Ontario’s Snowbelt on Thursday With Up to 20 to 50cm Expected

December 03, 2025/ Brennen Perry

Intense but brief snow squalls are expected to return to parts of the snowbelt region around Lake Huron and Georgian Bay early Thursday morning with the arrival of a blast of brisk Arctic air. These squalls have the potential to bring heavy snowfall and near-zero visibility in the hardest hit areas.

Conditions are certainly ripe for more extreme, long-lasting squalls; However, the latest model data suggests this round will be cut short as shifting winds prevent the bands from locking in place for any prolonged period of time.

Snow squalls developing off Lake Huron will follow a west-northwest flow with the most intense activity aimed at the northeastern shoreline, which includes much of Grey Bruce. Another band off Georgian Bay will have a less steady flow, making the Lake Huron squall the stronger and more focused of the two.

This band is expected to remain mostly stationary through much of the morning and possibly into the early afternoon before slowly weakening later in the day. Hazardous conditions are expected in this zone with complete whiteouts, blowing snow and rapid snowfall rates of 4 to 6cm per hour.

The hardest hit areas are likely to be around Port Elgin, Kincardine and Owen Sound where a band could set up early and barely move until the afternoon as winds ease and the squall dissipates. The reach of this band may stretch inland into parts of Grey County at times, including Meaford, Chatsworth, Flesherton and Hanover. Some areas could be digging out from significant totals by the end of the day.

Meanwhile, over Georgian Bay, shifting wind directions will make things much less predictable. The squall here will likely spread snowfall over a wider area rather than focusing on one region, mainly due to the flow swinging from westerly to northwesterly throughout the day.

It will likely begin with a westerly flow during the early morning, which would start the band in southern Muskoka, including MacTier, Bala, Bracebridge and Gravenhurst. It may also extend at times into southern Haliburton and northern Kawartha Lakes.

As winds turn more northwesterly, the band will slide down along the Hwy 400 and 11 corridor into northern Simcoe County, affecting Midland, Orillia and Washago. Travel in this region during the morning and early afternoon should be avoided if possible, as conditions will be quite poor.

There is still some uncertainty regarding the intensity of this Georgian Bay band, as shifting winds tend to weaken squalls and make them less organized. If it becomes even briefly stationary, that would likely be the period where snowfall intensifies.

How long the band can hold together before winds lock into a true northwest flow will determine totals for areas such as Barrie and the southern portions of Kawartha Lakes. By the early afternoon, the squall will have sunk into Wasaga, Oro and Barrie, but once the wind shift finalizes, the band will quickly lose its structure and begin to fizzle out.

If the squall lasts only into the mid-afternoon, Barrie may end up closer to 10cm. If it somehow holds into the evening, totals closer to 30cm would be possible.

All snow squall activity is expected to taper off by Thursday evening across Southern Ontario, although some light snow may linger overnight into Friday morning in areas closer to the lakes.

For Northern Ontario, snow squalls off the southeastern shoreline of Lake Superior will develop overnight and persist through much of Thursday. Sault Ste. Marie and the Wawa region may pick up 30 to 50cm by the end of the day. That lake effect activity is expected to weaken Thursday evening as a weak system shifts the wind direction.

Snowfall totals will vary widely due to ongoing uncertainty about the exact placement and duration of the bands. Confidence is highest that the Lake Huron squall will remain more focused compared to the Georgian Bay band.

As a result, the hotspot includes Port Elgin, Owen Sound, Hanover and Chatsworth, where 30 to 50cm is expected, with some models even hinting at localized pockets approaching 60cm.

The rest of Grey and Bruce counties are looking at 15 to 30cm, although totals may vary significantly depending on how far inland the squall extends and whether it drifts south into northern Huron and Perth counties.

Areas farther south and inland, including the rest of Huron and Perth counties, Wellington, Dufferin and Collingwood can expect around 5 to 15cm, but there is still a chance for much lower amounts if the band does not stretch that far.

A large zone along the Hwy 400 and 11 corridor from MacTier and Gravenhurst in the north to Barrie in the south, including Midland, Washago, Orillia and Wasaga, is expected to see the highest totals from the Georgian Bay squall.

At this point, 15 to 30cm appears likely, although localized totals up to 40cm are possible should the squall stall for any period of time. If that occurs, the most probable region for this is somewhere between Midland and Orillia.

The rest of Muskoka, Parry Sound, Haliburton, Kawartha Lakes and northern York and Durham regions can expect between 5 and 15cm, depending heavily on how far inland the Georgian Bay squall is able to stretch.

Elsewhere across Southern Ontario, less than 5cm is expected by the end of Thursday.

November 29, 2025

Yet More Snow on the Way for Southern Ontario With a Snowy System on Sunday Bringing Up to 10-20cm

November 29, 2025/ Brennen Perry

As many communities in the snowbelt regions around Lake Huron and Georgian Bay are currently digging out from locally over 50cm of snow from squalls over the past two days, another snow maker is already on the way, just in time for the final days of November.

Instead of very isolated pockets seeing intense snowfall totals as we have seen with the lake effect activity, this system will spread accumulating snow across almost all of Southern Ontario. Widespread totals by the end of the weekend are expected to range from 5 to 15cm, with locally as much as 20cm in the areas that remain colder for longer.

Snowfall is expected to begin moving in from the west by late Saturday evening, starting first across Deep Southwestern Ontario. By the middle of the overnight, steady light to moderate snowfall will extend across almost all of Southern Ontario as the system further progresses into our region.

By late Sunday morning, southwesterly winds flowing across the still warm waters of Lake Erie and Lake Ontario are expected to push temperatures several degrees above freezing along the northern shorelines. This may allow the last remaining few hours of precipitation to switch over to rain for some communities right along the lakeshore.

There could also be a lake effect component to this system as it departs our region to the east. As this happens later in the day on Sunday, we may see locally heavier pockets of lake effect snow develop east of Lake Huron and Georgian Bay, which also happens to include some of the same areas hit hard by the squalls over the last few days. This could push weekend totals into the 20 to 25cm range, especially if these bands linger longer into Sunday night.

Looking ahead to the start of the week, Monday should be fairly quiet as the lake effect activity tapers off early in the morning and the remaining flurries from the system fizzle out. It will certainly be colder with everyone seeing temperatures plunge below freezing. However, that calm weather may be short-lived.

There are early indications of another potential system sliding south of the Great Lakes region. Depending on the track, this could bring another round of heavy snow throughout the early part of Tuesday, especially for areas further southeast.

The initial bands of snowfall associated with the weekend system will begin to enter Southwestern Ontario from the west sometime just after the dinner hour on Saturday.

For most areas, the snowfall should be fairly light at first, but some models are showing the potential for several hours of heavier snowfall rates approaching 2 to 4cm per hour for Windsor, Leamington and Chatham. This could lead to a quick 5 to 10cm by the end of the night if the heavier bursts materialize.

As we head into the overnight hours, the system is expected to continue spreading eastward across Southern Ontario, with almost all areas seeing steady snowfall by the middle of the overnight.

Snowfall rates are not expected to be overly extreme, with most regions seeing less than 1cm per hour through Sunday morning. Even still, this snowfall is expected to continue for 6 to 12 hours, which will allow the totals to gradually build up.

Because the snow will be more widespread and less intense than recent squall activity, road crews should be able to keep up with the conditions on most major routes. Travel delays are still likely, so if you do need to drive, be sure to leave plenty of extra time and adjust your speed based on the conditions.

Winds are expected to pick up through the later part of Sunday morning, coming out of the southwest, and flowing across Lake Erie and Lake Ontario. This will push warmer air into the northern shorelines, which may allow the snow to switch over to rain directly along the Lake Erie and Lake Ontario shorelines.

Due to this transition, slightly lower snowfall totals are expected here, and some areas may struggle to reach the 5cm mark. This includes the Greater Toronto Area near the lakeshore, along with Port Colborne, Norfolk County, Tillsonburg, St. Thomas and Rondeau.

The system is expected to gradually taper off through Sunday afternoon, leaving scattered flurries in its wake into the evening. This leftover precipitation is likely to be enhanced by Lake Huron and Georgian Bay through Sunday evening and into the overnight hours.

Expect an additional 5 to 10cm of snowfall on top of the system totals in the areas that see lake effect enhancement. This could push the end-of-weekend totals to locally as much as 20 to 25cm in the traditional snowbelt regions.

When it comes to the distribution of precipitation, we expect it to fall fairly evenly across the province. However, snowfall totals will vary based on temperature differences, which will influence how efficiently the snow can accumulate.

The higher snowfall totals from this event are expected in the more northern sections of Central Ontario and extending into the Sudbury and North Bay region. This includes Parry Sound, Muskoka, Algonquin Park and Bancroft.

These regions will see more sustained below freezing temperatures throughout the event, along with lake effect enhancement late Sunday. With this, we are looking at around 10 to 20cm, with locally up to 25cm possible in the heavier lake effect pockets.

A similar situation is expected east of Lake Huron and along the higher elevations of the Dundalk Highlands and Oak Ridges Moraine, where slightly colder temperatures will help accumulations. Expect 10 to 20cm in these areas as well, with localized totals around 25cm, especially east of Lake Huron.

Everyone else, with the exception of the Lake Erie and Lake Ontario shorelines, is looking at a general 5 to 10cm. Some areas could see locally up to 15cm if temperatures end up just a bit cooler than expected. This includes the rest of Southwestern Ontario into Windsor, Chatham and Sarnia, the Lake Simcoe region and parts of the Ottawa Valley.

For communities exposed to the shorelines of Lake Erie and Lake Ontario, which includes Toronto, Oshawa, Oakville, Hamilton, Niagara-on-the-Lake, Port Colborne and Rondeau, snowfall totals will likely be closer to the 2 to 5cm range due to the warmer air intrusion and rain mixing during the latter part of the system.

As we look into next week, we are closely watching another potential system that could have an impact on Southern Ontario throughout the day on Tuesday. There is still some uncertainty on the exact track, with the latest model runs shifting it slightly further north, which would increase impacts across a wider portion of the region. However, it could easily shift back south.

At this point, we can say there is a decent chance of 5cm or more across a wide stretch of Southern Ontario, with the highest probability being further southeast, including the Niagara region and communities along the St. Lawrence River. Be prepared for possible impacts to the Tuesday morning commute, including the potential for school bus cancellations if the system trends stronger.

Expect possible impacts to the morning commute on Tuesday, including possible school bus cancellations, should we see a stronger system.

November 27, 2025

BIG CHANGES Coming to Environment Canada’s Alerts Beginning Today

November 27, 2025/ Adam Skinner

Environment Canada is making big changes to the way it issues weather alerts, in an attempt to make them easier to understand at a glance.

Starting today, Wednesday, November 26th, 2025, the new system will use Yellow, Orange or Red colours for all 'Advisories', 'Watches' and 'Warnings'.

'Statements' will remain unchanged (blue or grey), for now.

Environment Canada is making this change to hopefully help you quickly gauge both the severity of a weather event and the level of confidence forecasters have in their predictions.

Shown in the chart above, Environment Canada forecasters will choose the colour of alerts based on an "Impact" level and a "Confidence" level.

Here’s a breakdown of the upcoming changes and what they mean for you.

Headline Changes

Currently, weather alert headlines look like this:

Heat Warning

Under the new system, the headline will include a colour code that signals risk. For example:

Yellow Level Warning – Heat

We at Instant Weather feel that something about "Yellow Level Warning – Heat Issued" looks… strange and extra confusing.

Therefore, when we post Environment Canada alerts to social media, send notifications via our free app, and send out text message alerts, we're going to format it like this:

Heat Warning (Yellow Level) Issued

We believe this will make the transition from the old format to the new format easier for our community members. However, we'd love to hear your feedback on this so please let us know what you think about it!

NEW COLOURS

For the first time, advisories, watches and warnings will come in one of three colour options:

- Yellow = low risk (stay alert)

- Orange = moderate risk (take precautions)

- Red = high risk (serious danger)

Impact Level

The new Impact Level will estimate how much damage or disruption a storm is likely to cause.

Possible values:

- Low

- Moderate

- High

- Extreme

For example, a minor snowfall could be flagged as low impact, while a hurricane might carry an extreme impact designation.

Confidence Level

The new Confidence Level should help clarify how confident the Environment Canada forecaster issuing the alert feels.

Possible values:

- Low

- Moderate

- High

- Very High

For example, a “very high confidence” alert means there's near zero question if the storm poses a threat to the alerted area, while a “low confidence” could suggest that path may shift direction or the storm could dissipate.

Why These Changes Matter

Environment Canada believes these updates make weather alerts more actionable and accessible. Instead of vague warnings, you’ll know:

- The severity of the threat (colour level).

- The expected damage (impact level).

- The certainty of the forecast (confidence level).

For further details on these alert changes, visit Environment Canada’s newly launched website regarding colour-coded alerts:

https://www.canada.ca/en/services/environment/weather/severeweather/weather-alerts/colour-coded-alerts.html

November 26, 2025

Dangerous Snow Squalls Target Southern Ontario’s Snowbelt Starting Thursday With Up to 75cm of Snow Possible

November 26, 2025/ Brennen Perry

Confidence continues to grow in what is shaping up to be a potentially dangerous snow squall event for regions east of Lake Huron and southeast of Georgian Bay as we wrap up the week.

Temperatures are expected to drop sharply overnight Wednesday, which will help kick the lake effect snow machine into gear as early as Thursday morning.

At first, the activity should be fairly limited. Scattered pockets of lake effect snow are expected to develop east of Lake Huron and Georgian Bay as a westerly wind pattern holds through the morning. Impacts will be minor at this stage, but this early activity will set the stage for a much more intense setup later in the day.

Rapid changes are expected by late Thursday morning and especially into the afternoon. This is when more organized squalls will begin to form.

The worst conditions are expected to develop late Thursday and last into Friday morning. A brisk northwesterly wind will allow narrow but powerful bands of snow to strengthen off both Lake Huron and Georgian Bay. These bands will be capable of producing snowfall rates near 5 to 10 cm per hour at times, along with near-zero visibility.

Travel will likely become extremely difficult through the hardest hit regions. Strong winds will create blowing snow and possibly even brief blizzard conditions. Road closures are possible, and anyone with non-essential travel plans should consider postponing. School bus cancellations appear likely for Friday, and there is even some potential for cancellations on Thursday, depending on how quickly conditions deteriorate.

The main snow squall activity is expected to taper off throughout the day on Friday, although some scattered bands could linger into Saturday. By the end of the day Friday, some areas east of Lake Huron, such as Goderich, Kincardine and Stratford, may be digging out from more than 40 cm of snow. Other parts of the snowbelt may see anywhere from 10 to 40 cm, depending on how close they are to the core of the activity.

As mentioned earlier, Thursday morning will start with some light to moderate activity east of Lake Huron and Georgian Bay. This includes Grey Bruce, Parry Sound and Muskoka.

Impacts should be limited at first since the snow will be fairly light, but Environment Canada currently has a snow squall watch in effect for this entire region due to what will likely unfold later in the day.

Conditions will escalate quickly heading into the late morning and afternoon as scattered flurries begin organizing into more defined bands. We expect a fairly long squall to develop over Lake Huron, cross the Bruce Peninsula and come onshore east of Georgian Bay. This could bring a few hours of heavy snow to the Muskoka region.

Additional pockets of lake effect snow may also fire up further south off Lake Huron, affecting areas like Goderich, Hanover, Stratford and Kitchener.

That Georgian Bay squall is expected to gradually sink southward as the wind shifts from westerly to northwesterly. This will cause a swath of intense snow to drift across the Highway 11 and 400 corridor between Bracebridge and MacTier, down toward Barrie.

A few hours of rapid whiteout conditions are possible during the afternoon. Even though temperatures may hover near the freezing mark, which slows accumulation, visibility will still be extremely poor and blowing snow will create dangerous travel conditions.

Conditions will worsen significantly into the evening as the squall drifts far enough south to draw its full moisture supply from Lake Huron instead of Georgian Bay. This new orientation will allow the band to tap into a longer stretch of open water, which increases its intensity.

At this point, several intense bands could stretch inland between Kincardine and Goderich and reach as far east as Kitchener and even the western GTA at times.

There is still some uncertainty in how these bands will align. A slight shift in wind direction can cause a squall to lock in place further north or drift south. This will dramatically affect who sees the heaviest snow. Regardless, conditions will be poor even in areas that are not directly underneath a streamer due to the blowing snow.

Within the core of the squalls, snowfall rates of 5 to 10 cm per hour will be possible. Thundersnow and lightning cannot be ruled out, given the strength of the setup.

Georgian Bay will see a brief lull with lighter pockets of snow affecting the South Muskoka to Simcoe County corridor. This break will be short-lived as winds shift yet again heading into the overnight hours.

The most dangerous conditions are likely overnight Thursday into Friday morning. A very intense squall off Lake Huron is expected to set up somewhere between Goderich and Kincardine and stretch inland toward regions between Kitchener and London.

There is still uncertainty about the exact placement. Even a tiny shift in wind direction could pin this band farther north or push it farther south. At times, it may also extend into Hamilton and the Niagara region with quick bursts of heavy snow and whiteouts.

Southeast of Georgian Bay, more organized bands are likely to develop from Barrie into Kawartha Lakes. Some of this activity may also clip the northern GTA, including York and Durham. The Georgian Bay squall will likely be weaker than the Lake Huron band, but model trends have strengthened it slightly in the latest data. Peak snowfall rates will likely sit around 3 to 6 cm per hour in the strongest areas.

Temperatures will plunge well below freezing overnight which will help snow accumulate far more efficiently.

Most model data suggests that the lake effect bands will remain locked in place through Friday morning, although the intensity may gradually decrease during the afternoon as winds begin to ease. Snow squalls could continue into Saturday, but confidence drops for the weekend pattern since the bands may become more fragmented and less organized.

As always with lake effect snow, exact totals are extremely difficult to predict. These events can produce huge differences over very short distances. One community could pick up 50 cm while another, only a few kilometres away, sees barely any accumulation.

Even with this uncertainty, the most consistent model signal points toward a high-impact zone east of Lake Huron, picking up a general 40 to 75 cm of snow by Friday evening. This includes Goderich, Point Clark, Kincardine, Mildmay, Wingham, Clinton, Mitchell, Listowel and Stratford.

Localized totals near 100 cm cannot be ruled out, although these would be isolated pockets rather than widespread amounts.

A wider zone east of Lake Huron that stretches into the Kitchener area has the potential to see 20 to 40 cm of snowfall accumulation.

For Georgian Bay, the squall should be weaker than the Lake Huron band. We are going with 20 to 40 cm for regions like Collingwood, Wasaga Beach, Midland, Orillia, Barrie, Innisfil, Angus and Keswick. This may end up being a slight overestimate if the squall fails to organize as we saw in the last event, which significantly underperformed.

Muskoka, Parry Sound, Kawartha Lakes and parts of the eastern GTA may see 10 to 20 cm depending on how far the bands push inland.

Less than 10 cm is expected for the rest of Southern Ontario, including Eastern Ontario, the Golden Horseshoe and deep Southwestern Ontario, since they will be far enough removed from the main lake effect activity.

November 23, 2025

Widespread 5–15cm of Fresh Snow to Blanket the Southern Prairies Early This Week

November 23, 2025/ Alannah Campbell

As we get closer to the start of the storm expected to cross the Prairies and weather models have come closer in agreement, we now have more confidence to discuss the potential impacts over the next couple of days. This storm will travel eastward along the international border, which will limit most of the snowfall to southern portions of all three Prairie provinces.

Alberta

The snow will make its way into Southwestern Alberta after midnight, gradually spreading eastward across the province during the early and mid-morning hours. It’s during this time that there is also a risk of freezing rain for communities closer to the border, but it will quickly be replaced by snow. Meanwhile the scattered flurries remaining from Sunday through Calgary to Red Deer are also expected to organize and intensify, joining the snow further to the south.

***The rdps model showing precipitation type and intensity at 7am MT on Monday, courtesy of WeatherBell.***

As we get later in the morning, there will likely be some intensification and increased snowfall rates along the Highway 3 corridor and southward, which will result in greater overall accumulation. By lunchtime, the snow will begin to taper off to the north of Calgary and then from west to east starting in the early afternoon and exiting the province completely in the evening.

A widespread 5-15cm of snow is predicted by the end of Monday across Southern Alberta and areas that experience the heavier snowfall closer to the border could be on the higher end of that range. There could be pockets where accumulation totals could approach 20cm to the south of Highway 3, but this is much more likely to occur east of Highway 36.

***The rdps model showing precipitation type and intensity at 7pm CT on Monday, courtesy of WeatherBell.***

Saskatchewan

The leading edge of the snow will move into Southwest Saskatchewan in the mid-morning and it will spread eastward across the province through the day. There is also the slight risk for some freezing rain along the border to the south of Maple Creek and Shaunavon, but it should be over quickly.

The snowfall across Saskatchewan will be fairly short-lived and by the time the snow reaches the Manitoba border in the evening, it will actually start to taper off back along the Alberta border. Throughout the remainder of the evening, overnight and into Tuesday morning, the snow will gradually end from west to east.

Similarly to in Alberta, much of Southern Saskatchewan can expect at least 5cm of snow by midday Tuesday. There will also be heavier snowfall from Maple Creek to Estevan, mostly along Highway 13 and southward. This particular region will likely see snowfall totals around 20cm and Environment Canada may issue a snowfall warning to reflect this.

***The rdps model showing precipitation type and intensity at 7am CT on Monday, courtesy of WeatherBell.***

Manitoba

By the time the snow makes its way into Manitoba Monday evening, the entire system is expected to shift course and start moving more in a southeast direction as it interacts with another low pressure system from the States. As a result, the steady moderate snowfall will not extend as far east through the province. Regardless, the snow will still make its way across Southern Manitoba overnight and into Tuesday morning. It will slowly start to taper off from west to east around sunrise, gradually ending for border communities in the Eastman Region Tuesday evening.

The system will also start to weaken as it makes its way into Manitoba, so the heavier snowfall expected in both Alberta and Saskatchewan is looking like it won’t be as much of a concern. There will still be a swath of the region that can expect more than 5cm of snow by the end of Tuesday, but it is likely that this won’t exceed 10cm.

It is possible that this change in direction is more subtle than showing on weather models or doesn’t occur at all. We will watch as the system takes shape and makes its way through Alberta and Saskatchewan. If it appears that the track will change from what was initially expected, it’s likely that we will update our forecast for Manitoba.

As it stands, a decent amount of snow is expected to fall across the Southern Prairies. This snow will be heavy in some areas, which will likely make travel a headache, especially on some of the busier highways. Be sure to give yourself plenty of extra time if travelling during these periods of heavy snowfall and stay safe.

November 15, 2025

Snow Squalls Take Aim at London, Barrie and Northern GTA on Sunday With Up to 25-50cm of Snow Possible

November 15, 2025/ Brennen Perry

We enjoyed a brief break from the wintry weather on Saturday as temperatures soared into the double digits across much of Southern Ontario. The exception was Eastern Ontario, where the Ottawa Valley dealt with hours of freezing rain.

But that warm spell is going to be short-lived. Cooler air returns overnight into Sunday, and temperatures will slide back below the freezing mark. Once that happens, the lake effect snow machine will fire up again for the next couple of days.

And no, it isn’t déjà vu. The target zone for this round of squalls will look very similar to last week’s event, but the focus shifts slightly east. That puts areas like London, Barrie and even the Northern GTA, including York Region, in line to be hit hard.

By the time the squalls wind down on Monday, the hardest hit spots could be digging out from more than 25cm, with the potential for very localized pockets of 50cm.

We expect the snow squall activity to begin ramping up late Sunday morning. As temperatures fall, lake effect rain bands will flip over to snow off the southeast shoreline of Lake Huron and Georgian Bay.

While the changeover happens in the morning, ground temperatures may stay just above freezing for several hours. This means the first few hours of snow could melt on contact. Accumulation will start later in the day once temperatures reach the freezing mark.

Even before the snow begins to stick, visibility will drop quickly. Those in the affected areas should expect sudden whiteouts and dangerous driving conditions.

**Hourly snowfall rate (cm)** - MAP FROM WEATHERBELL

By the dinner hour, the squalls will become much more organized. Snowfall rates from the Lake Huron band could rise to 5cm per hour. This main band is expected to extend from Lake Huron through Goderich and southern Huron County into the London region.

Additional squall activity will form southeast of Georgian Bay, running from the shoreline through Barrie and Angus and into Newmarket and Durham. This band looks weaker than the Lake Huron squall at first, but could still deliver rates of 2 to 4cm per hour.

The worst conditions are likely around midnight. The Lake Huron band is expected to lock onto London, bringing intense snow and rapid accumulation of 6 to 8cm per hour.

The Georgian Bay squall will also strengthen, sliding south of Barrie and focusing on Angus, Bradford and Newmarket. Some signals show it reaching into the Eastern GTA, including Scarborough, Ajax and Oshawa.

These squalls should remain mostly stationary overnight, although minor drifting is possible. As temperatures fall several degrees below freezing, expect snow to pile up quickly.

By mid-morning Monday, the bands will begin to weaken as winds shift more westerly. Some lake effect flurries could linger east of Lake Huron into Grey Bruce, but they are not expected to be very organized. Everything should taper off by late Monday.

Snow squall forecasting always comes with big caveats. The bands are extremely narrow, which means the difference between 50cm and almost nothing can be only a few dozen kilometres.

This is why we provide a broad range. They help capture that uncertainty, but they are not a guarantee. With this event, the bands appear very intense but also very narrow, which means gradients will be sharp.

Based on the latest data, we expect the hardest hit areas from the Lake Huron squall to include Goderich, Clinton, Lucan, Exeter, Mitchell and London. Snowfall totals here could range from 25 to 50cm, with the chance that someone ends up over 50cm in a very localized spot.

Surrounding regions, including Grand Bend, Tillsonburg, Stratford, Wingham, and Point Clark, could see 15 to 25cm.

Further east into Grey Bruce and Dufferin County, we are expecting 5 to 15cm mainly on Monday as the lake effect shifts northward.

The Georgian Bay band looks even narrower than the Lake Huron band. A small corridor stretching from Collingwood through Angus and into Innisfil could see 25 to 35cm, with a chance of 50cm if the band really intensifies.

The City of Barrie is right on the edge. A small shift north or south would bring very different results. For now, the highest totals look likely in the south end of the city with 15 to 30cm. The north end may be closer to 10 to 20cm.

Substantial totals may also extend into the Northern GTA, including Bradford, Newmarket and Aurora. Totals along the Highway 400 and 404 corridor could range from 15 to 30cm.

Across the east end of Toronto and Durham, including Ajax, Pickering and Oshawa, occasional heavy bursts may bring 5 to 10cm.

The rest of Southern Ontario should see less than 5cm of snow by Monday from the lake effect.

November 10, 2025

Snow Squalls Could Bury Parts of Southern Ontario’s Snowbelt in Up to 50cm of Snow Early This Week

November 10, 2025/ Brennen Perry

As much of Southern Ontario cleans up after our first widespread snowfall of the season, Mother Nature is showing no signs of slowing down. The lake effect snow machine is roaring to life over Lake Huron and Georgian Bay as we kick off the second week of November.

Snow squalls have already developed south of Lake Huron late Sunday evening and are expected to strengthen through the night. We’re also anticipating some squall development along the southern shoreline of Georgian Bay, which should organize by Monday afternoon or evening.

Two main regions are likely to see the most intense activity. The first stretches between Sarnia and London, while the second includes areas south of Georgian Bay from Blue Mountain and Meaford toward the west of Barrie. Both zones could see heavy snow squalls lasting through to Tuesday morning.

While snowfall totals will vary significantly across short distances, confidence is increasing that the hardest hit areas could see as much as 25 to 50cm by the time the squalls taper off on Tuesday. Localized pockets may even exceed 50cm, depending on where the heaviest bands set up.

Road conditions are expected to deteriorate quickly in these regions, with road and highway closures likely late Monday and into early Tuesday when the most intense squalls occur. Travel should be avoided unless absolutely necessary, as these bands can produce sudden whiteouts, making it nearly impossible to see the road ahead.

**ESTIMATED AIR TEMPS AROUND 1.5KM ABOVE GROUND** - MAP FROM WEATHERBELL

This setup is being fueled by a rare November appearance of a mini “Polar Vortex” which is pulling a blast of Arctic air into Southern Ontario. This cold air is flooding the upper levels of the atmosphere and setting the stage for intense lake effect activity.

To put it simply, when forecasters talk about 850mb temperatures, we’re referring to the air temperature roughly 1.5 kilometres above the ground. This level helps forecasters understand how cold the air mass is higher up in the atmosphere, which is critical for predicting lake effect snow.

Over the next few days, 850mb temperatures are expected to plunge into the negative teens. Lake effect snow forms when there’s a large temperature difference between the lake surface and the air above it, generally 13°C or greater. With upper air temperatures between -10°C and -15°C and lake temperatures still above 10°C, that difference is more than 20°C, creating ideal conditions for lake effect snow to thrive.

As of midnight, snow has already developed off the southern shores of Lake Huron, impacting the Sarnia region. So far, the bands have been disorganized and spread out, but that’s expected to change by late Monday morning as a stronger, more focused squall forms somewhere between London and Sarnia.

While the exact placement remains uncertain, areas near Petrolia and Strathroy appear most likely to be in the direct path. The band will likely shift through the day as wind directions fluctuate, leading to varying snow intensities across nearby towns.

By Monday evening, things will really start to ramp up. The main squall off Lake Huron will likely push inland, with a more northwesterly wind direction steering it toward Grand Bend, Goderich and potentially the western edges of London. It’s still unclear if the squall will reach directly into London or remain just outside the city, but if it does, the heaviest snowfall will likely fall on the west side.

Meanwhile, snow squalls are expected to organize over Georgian Bay with heavy snow bands developing between Owen Sound and Barrie. There’s still some disagreement among models, with some focusing more on Wasaga Beach and Barrie while others favour a southern shoreline setup.

An interesting twist could occur if these Georgian Bay bands extend far enough inland to be enhanced by Lake Ontario. In that case, snow could reach into the western GTA and even the Niagara region, leading to sudden bursts of heavy snow if everything aligns.

This lake effect activity is expected to persist overnight and into Tuesday morning, though the Georgian Bay bands should weaken slightly around sunrise. West of London, however, heavy snow could continue well into Tuesday morning before breaking apart as conditions become less favourable later in the day.

As always with lake effect snow, totals are extremely difficult to pinpoint. These narrow bands can stay locked over one community for hours while completely missing another just a few kilometres away. One person may end up shovelling half a metre of snow while someone nearby barely sees a dusting.

That said, two areas consistently stand out across the latest model runs. One includes Lambton Shores, Grand Bend and Strathroy, while the other covers the southern Georgian Bay shoreline and higher terrain around Blue Mountain. These regions could see totals ranging from 25 to 50cm by Tuesday.

Surrounding communities such as Petrolia, Thamesville, St. Thomas and Lucan, along with Orangeville, Shelburne and Flesherton, are more likely to see 15 to 25cm.

Both London and Barrie sit right on the edge between lighter and heavier accumulations. We currently have them in the 5 to 15cm or 15 to 25cm zones, depending on how far east the snow squalls extend.

Finally, the Niagara region remains uncertain. If the Georgian Bay squalls stretch far enough inland and connect with Lake Ontario, parts of the region could pick up over 15cm of additional snow.

Outside of these snowbelt regions, impacts will be much less significant. A few flurries and brief bursts of snow are possible as the squalls wobble, but most areas outside the direct lake effect zones should remain relatively calm through Tuesday.

November 08, 2025

Snowy Sunday Sweeps Into Southern Ontario With First Widespread Snowfall of the Season

November 08, 2025/ Brennen Perry

While there has been a lot of uncertainty surrounding Southern Ontario’s first widespread snowfall event of the season, we’re finally starting to get a clearer picture of what will unfold on Sunday. After several model shifts over the past few days, the latest data is now coming into better alignment, giving us a more confident idea of how this system will behave.

A developing low-pressure system is expected to move in from the southwest late Saturday night, tracking across areas near Lake Erie through the day on Sunday. As it does, it will bring a broad swath of snow stretching from Windsor through the Golden Horseshoe and into Eastern Ontario. Snow is expected to last much of the day before gradually tapering off overnight.

At this stage, snowfall totals are expected to vary quite a bit across the region. The exact placement of the heaviest snow bands remains uncertain, and surface conditions will also play a big role. Since the ground is still relatively warm, some of the early snowfall may melt on contact before it can begin to accumulate, especially on roads and sidewalks.

In general, by Monday morning, snowfall totals are expected to range from around 5 to 10 cm across the Golden Horseshoe and into Eastern Ontario. Within those areas, localized pockets, particularly in Eastern Ontario, could pick up as much as 15 to 20 cm according to the latest model runs. Further north and west, across Central and Southwestern Ontario, amounts will be lower with less than 5 cm expected in most spots.

As the system departs, colder air will pour into Southern Ontario late Sunday night, sending temperatures well below freezing. Any slushy snow or water on roads, sidewalks, and driveways will freeze quickly overnight, which could create slick conditions for the Monday morning commute. Drivers should be prepared for icy patches, and there’s a decent chance of school bus cancellations in areas that see higher snowfall totals.

The colder air will also fire up the lake effect snow machine early next week. Model guidance suggests that an intense but narrow band of snow could form southeast of Lake Huron late Monday and continue into Tuesday. This could impact communities such as Grand Bend and London, where local snowfall totals could exceed 25 cm if the band remains stationary for an extended period.

For timing, snow is expected to begin in Deep Southwestern Ontario shortly after midnight. Around Windsor and Chatham, it may even start as rain before transitioning to snow as temperatures drop closer to dawn.

By late Sunday morning, the snow will have spread into the Golden Horseshoe, becoming heavier through the afternoon. In Eastern Ontario, snow will likely begin around Kingston early in the morning and reach the Ottawa area by midday.

The heaviest snowfall rates across the Golden Horseshoe are expected from early to mid-afternoon, with some models projecting bursts of 2 to 4 cm per hour at times before tapering off toward the evening.

For Eastern Ontario, steady snow will continue through the afternoon, peaking after dinner before easing into scattered flurries overnight. With that timing, school bus cancellations are quite possible for parts of Eastern Ontario on Monday.

There are also some indications that freezing rain or ice pellets may mix in along the international border Sunday evening. Areas such as Kingston, Brockville, and Cornwall are most at risk for this brief mix, which could add an extra layer of slickness to untreated surfaces.

While there is still some disagreement among the models on exactly where the heaviest snow will fall, the general expectation remains 5 to 10 cm along the Golden Horseshoe and into Eastern Ontario, with some locally higher amounts near 15 cm.

We’ve outlined portions of Eastern Ontario and the higher elevations of the Niagara region on our map with a dotted zone, representing areas that could overachieve and see closer to 20 cm. However, that outcome is far from certain.

Keep in mind that this is the first significant snowfall of the season, and with ground temperatures still above freezing, actual accumulation could vary from one street to the next. Some areas may see a quick coating, while others struggle to hold the snow through the day, especially near the lakeshores.

Elsewhere, Southwestern Ontario and much of Central Ontario should see lighter amounts, generally only a few centimetres, with some localized areas possibly reaching up to 8 cm. Regions like Grey-Bruce and the northern parts of Central Ontario will likely miss out on the heaviest snow this time, but that may not last long as lake effect activity ramps up early next week.

As higher-resolution models continue to come into range, we’re getting a clearer idea of what the first snow squall event of the season could look like. Current projections suggest activity will develop on Monday, with a more organized squall forming by the evening.

This band may set up somewhere between Grand Bend and Kettle Point, extending inland, likely just west of the City of London. Additional bands may also develop off Georgian Bay, impacting areas around Meaford and Collingwood.

Communities caught under these narrow squalls could see impressive snowfall totals, while just a few kilometers away, grass may still be visible. We’ll continue to refine the details as the event approaches and will have a more specific forecast on who could see the most snow closer to Monday.

Overall, this marks the true start of the winter season across Southern Ontario, with several systems and lake effect events lining up behind this one. It’s a good time to check that your winter tires are ready, snow shovels are handy, and morning routines include a few extra minutes to clear off your car. Winter is here to stay.

November 06, 2025

Southern Ontario to Plunge Into Winter as Sunday Snowstorm Could Dump Up to 20 cm of Snow

November 06, 2025/ Brennen Perry

It feels like just yesterday we were talking about record-breaking heat that stretched well into October. But November has been a completely different story, with winter now making its presence known across Southern Ontario. Those warm late-autumn days are coming back to haunt us, as the still-warm lakes are setting the stage for a series of snowy chances in the days ahead, including the lake effect snow machine coming to life.

Cold Arctic air is set to flood into the province, bringing several snowmakers with it, including a potential snowstorm on Sunday, followed by intense snow squalls early next week.

Our first system arrives on Friday, spreading across Ontario throughout the day. Southern Ontario will mainly see rain from this one, while Northern Ontario braces for a significant dumping of snow. Some areas could see close to 20 cm by Saturday.

As colder air rushes in behind this system, temperatures will plunge across Southern Ontario through Saturday night. By Sunday, much of the region will be below freezing, setting the stage for the next system expected to move in during the day Sunday. Early indications suggest that parts of Southern Ontario could see significant snowfall from this system, with totals possibly reaching up to 20 cm by Sunday night.

That said, there’s still plenty of uncertainty surrounding the exact track of the storm. A slightly more southern route could pull the heaviest snow into the Greater Toronto Area as colder air dips farther south.

The first round of precipitation will begin in Northwestern Ontario late Thursday, spreading across Northeastern and Southern Ontario by Friday morning.

**RAINFALL TOTALS** - MAP FROM WEATHERBELL

For most of Southern Ontario, this will mean a steady rainfall, with totals around 5 to 10 mm, although localized pockets near the lakes could see closer to 15 mm.

**SNOWFALL TOTALS** - MAP FROM WEATHERBELL

Higher elevations in Central Ontario, including Algonquin Park, could see some wet flurries mix in at times. Farther north, around Hearst, Kapuskasing, Cochrane, and Timmins, it’s all snow, with totals of 15 to 20 cm possible by Saturday morning.

Behind the system, much colder air will spill into Central Ontario overnight Friday into Saturday, dropping temperatures well below freezing. The rest of Southern Ontario will see the chill arrive soon after, with most regions seeing their daytime highs recorded just after midnight Saturday before temperatures tumble through the day.

By early Sunday morning, the cold will be firmly in place. Most areas will be below freezing, except for parts of Deep Southwestern Ontario and along the Lake Ontario shoreline where temperatures will hover just above zero.

This cold setup will pave the way for Sunday’s incoming system. Models are in disagreement about the storm’s path, which will ultimately decide who gets the heaviest snow. The American and Canadian models track the low across Lake Erie and Lake Ontario, placing the rain-snow line near the GTA.

In this scenario, areas north of the GTA, including parts of Southwestern Ontario, Lake Simcoe, and the Ottawa Valley, would see heavy snow, while the GTA experiences a mix of rain, ice pellets, and wet snow.

Even a small shift southward, as suggested by the European model, would change everything. That track takes the low through Pennsylvania and Upstate New York, shifting the heaviest snowfall into the GTA and surrounding regions, with totals over 15 cm.

In this case, the snow would stretch from London through the GTA, Peterborough, and into Ottawa, while Central Ontario and Grey-Bruce see lower amounts.

For now, most models favour the northern track, so that’s what we’re leaning toward in our preliminary forecast. But if the European solution proves right, those snowfall zones could shift south before the final forecast is issued.

Under the current setup, the heaviest snow is expected across a broad stretch of Southwestern Ontario, including the Lake Huron shoreline through Kitchener and up toward Barrie, Lindsay, and Peterborough, extending into the Ottawa Valley. These areas could see 10 to 15 cm of snow, with localized pockets near 20 cm possible.

The American NAM model is even more aggressive, suggesting up to 30 cm in some areas, though that’s likely overdone. The London area, GTA, and Eastern Ontario fall into a mixing zone, with 5 to 10 cm possible once precipitation switches to snow. Should the system shift farther south, those totals could increase.

Farther south, places like Windsor, Chatham, Sarnia, and the Niagara Region are expected to stay mostly rain, though a slushy 5 cm of snow is possible.

Snowfall will taper off by late Sunday, but the story won’t end there. Behind the storm, a strong surge of cold air over the still-warm Great Lakes will ignite a burst of lake-effect snow squalls on Monday.

The exact regions that will see the most intense squalls remain uncertain until higher-resolution models come into range, but areas downwind of Lake Huron and Georgian Bay should prepare for the potential of significant accumulations. Some communities could be digging out from 25 cm or more by early next week.

October 31, 2025

Snowy Scare: Frightful Flurries May Haunt Parts of Southern Ontario on Halloween Night

October 31, 2025/ Brennen Perry

After a soggy start to Halloween Eve across Southern Ontario on Thursday, a strong system will cast a gloomy spell over the region with widespread rainfall. But don’t be fooled, as that’s only a taste of what Mother Nature has brewing in her cauldron for Halloween itself.

Last year, we were treated to a mild and friendly Halloween with temperatures that felt more like a trick than a treat. This year, however, it looks like Halloween will send a real shiver down your spine as temperatures drop to levels more fitting for the undead.

Rain from Thursday is expected to linger overnight and into the early hours of Friday, heavy at times, especially across Eastern Ontario. The good news is that the worst of the rainfall should clear out just in time for trick-or-treating across Southwestern Ontario and the Golden Horseshoe. Temperatures will hover around what’s normal for this time of year, ranging from the mid to upper single digits, possibly reaching the low double digits in Deep Southwestern Ontario.

But it’s as if a witch has placed a chilling curse over Central and Eastern Ontario. As the rain lingers through Friday, some areas could begin to see strange white shapes drifting through the sky and no, they aren’t ghosts! These spooky apparitions are far more real, as rain could turn to wet flurries as early as Friday afternoon. Cold air will creep in like a Halloween fog, sending temperatures tumbling toward the freezing mark by evening.

While there’s some disagreement between models (a classic case of meteorological mischief), there’s solid agreement that a wide stretch of Central Ontario may experience at least a few wet flurries on Halloween night.

Where the models differ is in timing and intensity. Some are quite aggressive, conjuring an earlier and more widespread switchover to snow that could even allow for light accumulations in higher elevations. Others show a less frightful outcome, with flurries limited to the hills and highlands later in the day as the rain fizzles out elsewhere.

As we rise on Halloween morning, rain will still be haunting much of Southern Ontario, though it will begin to taper off from west to east.

That’s where the great model split begins. For this forecast, we’re focusing on the NAM (American) and HRDPS (Canadian) models, which represent two distinct camps. The European model seems to be siding with the Canadian solution.

The American model pulls colder air into Central Ontario faster, dropping temperatures a few degrees lower than the Canadian model. It might not sound like much, but when temperatures hover near freezing, every degree counts. This could allow snow to start mixing in by early afternoon.

Areas like Algonquin Park, Haliburton, Bancroft, and northern Muskoka may see the first flurries, with the “mixing zone” spreading south through the afternoon into Muskoka, northern Simcoe County, and the Kawartha Lakes region.

The Canadian model delays the switchover until closer to dinnertime, mainly over higher elevations.

By then, the precipitation in western areas may already be fading, keeping Muskoka and Simcoe County mostly rain-soaked rather than snow-covered.

If the American model’s spookier version plays out, several hours of heavy, wet snow could fall Friday evening. While the ground is still warm, we’ve seen before that a strong enough burst of snow can briefly overcome that warmth and start to accumulate.

This model also spreads the snowy risk zone further east, even hinting at flakes creeping into the Ottawa Valley.

The most likely areas to see actual snow include the higher elevations of Central Ontario, such as Sundridge, Huntsville, Algonquin Park, and Bancroft. These regions could even pick up a few slushy centimetres by night’s end if the stronger scenario comes true.

Elsewhere across Central Ontario, including Parry Sound, Bracebridge, Orillia, Kawartha Lakes, Tweed, and Pembroke, some wet flakes could mix in as trick-or-treaters prowl the streets. Accumulation isn’t expected here as the ground remains too warm, but it might add an extra eerie touch to the evening.

**ESTIMATED PRECIP OVER LAST 3 HOURS** - MAP FROM WEATHERBELL

As the ghosts, goblins, and ghouls hit the streets after nightfall, Southwestern Ontario will enjoy the calmest conditions, with rain clearing out hours earlier.

Central and Eastern Ontario, however, may not be as lucky. Light rain or even a few flurries could continue into the early evening, adding some spooky atmosphere to the night.

For the prime trick-or-treating hours, Deep Southwestern Ontario will be the mildest, with temperatures around 8 to 12°C at 8 PM. Elsewhere across the Golden Horseshoe and Eastern Ontario, temperatures will settle into the mid to upper single digits.

The chilliest readings will haunt Central Ontario, where places like Muskoka, Algonquin Park, and Bancroft may see readings near the freezing mark with flakes swirling through the air. Those heading out should make sure their costumes have a few extra layers because this Halloween, it’s not just the monsters giving people chills.

Have a Happy Halloween!

October 22, 2025

Southern Ontario Turns Chilly With a Chance of Early Season Flurries for Some Areas Friday Morning

October 22, 2025/ Brennen Perry

The feeling of change is definitely in the air across Southern Ontario this week. Fall colours are now past their peak in many areas, and a noticeable chill has taken hold across the region. The arrival of cooler air, combined with the still-warm Great Lakes, has kicked off another round of lake-effect precipitation off Lakes Erie, Ontario and Huron.

While it’s still warm enough to keep most of that precipitation as rain, the traditional “snow belt” east of Lake Huron and Georgian Bay will continue to see periods of lake-effect rain through Thursday and into Friday. Local rainfall totals of 25 to 50 mm are possible by Friday, especially east of Lake Huron.

However, not everyone will escape a touch of wintry weather this week. The latest model data suggests that temperatures could dip close to the freezing mark across parts of Central Ontario late Thursday night into early Friday morning. With some lingering showers still moving through the region, a few areas could see those showers briefly mix with wet flurries before sunrise on Friday.

The best chance to spot the first flakes of the season will be across Northern Muskoka (including Huntsville and Sundridge), Algonquin Park, Bancroft and North Bay. That said, precipitation will be very scattered, and not all of these locations will see snow. Even if flakes do fall, they won’t stick around for long as the ground remains too warm and temperatures will quickly climb above freezing later in the morning.

**ESTIMATED TOTAL RAINFALL BY FRIDAY** - MAP FROM WEATHERBELL

For those near Lake Huron and Georgian Bay, Thursday looks to be a wet one. Bands of lake-effect rain are expected to develop overnight Wednesday and linger through the day Thursday. As is typical with lake-effect events, rainfall totals will vary greatly over short distances depending on where the bands set up.

These bands are expected to wobble around through Thursday into Friday, spreading precipitation over a broader area rather than locking in on one spot. If one of the stronger bands does remain stationary for an extended time, localized flooding could occur, particularly near Kincardine and Goderich where some models show up to 50 mm of rainfall possible by Friday.

The lake-effect setup off Georgian Bay isn’t expected to be quite as strong, but parts of Simcoe County around Collingwood, Wasaga Beach and Barrie could still see locally up to 25 to 50 mm of rain. Again, the highest amounts will be very localized.

Elsewhere across Southern Ontario, expect occasional showers Thursday with generally less than 10 mm of rain as the heaviest precipitation remains confined to areas near the lakeshores.

By Friday morning, precipitation will gradually taper off as conditions become less favourable for lake-effect activity.

**ESTIMATED AIR TEMPERATURE on friday morning** - MAP FROM WEATHERBELL

Overnight Thursday into Friday, temperatures will drop into the low single digits across much of Southern Ontario, with some Central Ontario communities dipping to near or just below freezing.

While it’s not the first time this fall that temperatures have touched the freezing mark, what’s different this time is that lingering precipitation from both the lake-effect activity and a system over Quebec could overlap with those cold temperatures.

If any precipitation develops overnight, it could easily fall as wet flurries given the near-freezing surface temperatures and even colder air aloft that would favour snow instead of rain.

It’s worth noting that models disagree on how much precipitation will actually be present on Friday morning. Some may be underestimating light, scattered precipitation, which means there’s a chance flakes could be seen as far south as Huntsville and Bancroft. The most likely region for these flurries remains around North Bay and Algonquin Park, where multiple models consistently show light snow.

Unless you’re up early Friday morning, you’ll likely miss the brief appearance of the season’s first flakes. Any snow that does fall will melt quickly once temperatures climb above freezing, and no travel impacts are expected.

October 15, 2025

STORMY SUNDAY: Parts of Ontario Could Experience Damaging Wind Gusts & Flooding Risk This Weekend

October 15, 2025/ Adam Skinner

Environment Canada has released its latest medium range forecast, highlighting the potential for 70-90km/h damaging wind gusts across Southwestern Ontario, the Niagara regions and western GTHA regions on Sunday, October 19th, 2025.

They also mention a rainfall risk for Northeastern Ontario with the potential for 30-60mm of accumulation that could cause isolated flooding.

If this trend continues towards the weekend, it’s certainly possible that the ‘minor’ risk will be increased to a ‘moderate’ risk but seeing as we’re still four days out, it makes sense that Environment Canada is keeping the risk at the minor level.

Environment Canada does have a specific explanation for minor risks and it is: “This weather event is potentially significant or of interest. Users should stay informed.”

***NOTE: YOU CAN CLICK ON THE GRAPHIC ABOVE TO OPEN A ZOOMABLE IMAGE***

💨 Southern Ontario

Environment Canada writes in their forecast for Southern Ontario:

“Strong southwesterly winds with gusts of 70 to 90 km/h are likely for areas near Lake Erie and portions of southwestern Ontario. Winds will shift to northwesterly with the passage of a cold front late in the day, with gusts up to 90 km/h possible. Confidence is low regarding the timing and strength of winds expected.”

They also break down the risks:

Hazard(s): Wind

Location: Southwestern Ontario and western portions of the Greater Golden Horseshoe.

Timing: Sunday

Impact(s): Broken tree branches and downed trees. Power outages likely.

Confidence: Low (1 out of 4)

Impact: Moderate (2 out of 4)

🌧️Northeastern Ontario

Here are Environment Canada’s details for the rainfall risk in Northeastern Ontario:

”Significant rainfall is expected, with rainfall amounts of 30 to 60 mm likely. Confidence is low regarding the exact location of heaviest rainfall at this time.”

They also break down the risks:

Hazard(s): Rain

Location: Portions of northeastern Ontario.

Timing: Sunday

Impact(s): Possible flooding in low-lying areas.

Confidence: Low (1 out of 4)

Impact: Moderate (2 out of 4)

🔎 Staying Safe and Prepared

As we move towards the winter months, it’s critical to stay informed! To keep a close eye on our latest forecasts and get notified of any alerts, download our free app Instant Weather, available on Apple and Android devices.

Take a moment to secure any loose outdoor items before the storms arrive. Things like patio furniture, trampolines, and garbage cans can become projectiles in strong winds.

If you're planning to be on the roads, be prepared for challenging driving conditions such as sudden downpours, significantly reduced visibility, and the possibility of water pooling on roadways, especially in areas expecting heavier rainfall.

Stay safe everyone and if it’s safe to do so, share your reports with half a million community members on our Facebook group called Ontario Storm Reports!

Disclaimer: These forecasts are issued by Environment Canada and typically published via their Twitter/X accounts. We receive these forecast via a daily email and often publish them to help inform our communities.

October 09, 2025

Get Your Shovels Ready: Ontario's Snowbelt Could Be Buried Again This Winter

October 09, 2025/ Alannah Campbell

*Satellite image from GOES-16 shows lake effect snow coming off the Great Lakes on February 29th, 2024. Courtesy of* *CSU/CIRA & NOAA*.

The summer of 2025 was a hot one in Southern Ontario, in which we saw high temperature records consistently broken throughout the region. This trend has continued into October, with temperatures surpassing 30°C in parts of Southwestern and Eastern Ontario during the first weekend of the month.

Despite the fact that we’re gradually moving into the coldest part of the year, the heat from the summer and fall will continue to impact local weather conditions this winter. This will be particularly evident as lake effect snow, a phenomenon that occurs every year in the late fall and early winter in Southern Ontario.

The two main ingredients necessary for the development of lake effect snow are a large unfrozen body of water and a very cold air mass. The air mass needs to be at least 13°C colder at the 850mb pressure level of the atmosphere (this is typically found at around 1500 metres) than the temperature of the surface of the water. Once this threshold is reached, it’s like a switch being flipped and the lake effect snow machine starts.

There is more to the development of lake effect snow than just cold air and an open body of water. Another key component in lake effect snow development is moisture. Ideally, the relative humidity at the surface needs to be at least 80% for lake effect snow to form and levels below 70% could actually inhibit development. It can usually be assumed that the lake itself can provide enough moisture, but this is not always true. There also needs to be limited wind shear with height between the surface and the 700mb pressure level so that the moisture is more focused, sort of like a hose. The strongest, most organized bands of lake effect snow develop when the wind shear is less than 30°.

Finally is the concept known as “fetch”, which is the distance that the air mass travels over the lake. Fetch needs to be at least 100km in order for lake effect snow to develop and the greater the fetch, the more snow is produced. When considering prevailing wind directions, the traditional snowbelts are found in areas that are downwind of the greatest possible fetch over the Great Lakes, i.e. Buffalo and the entire length of Lake Erie.

*The creation of lake Effect Snow. Courtesy of Environment Canada.*

As the cold air mass travels over the much warmer surface of the lake, the warmth and moisture from the surface is transferred into the lower atmosphere. The warmer, moister air rises and it eventually cools and condenses, forming narrow bands of clouds. These clouds continue to travel over the open lake, gathering even more moisture, until they eventually reach land and the snow starts to fall at rates that can easily exceed 5cm per hour and could even be as high as 20cm per hour! It’s important to note that the hardest hit areas are actually not found immediately at the shoreline, but rather 30-50km inland from the lake.

The direction of the winds dictates which areas are hit by the lake effect snow so as long as the ideal conditions continue, so too will the development and subsequent falling of lake effect snow. This could lead to several days of heavy snow hitting the same area while there are sunny skies less than 20km away. A slight shift in wind direction can quickly change which area gets hit and that makes lake effect snow notoriously tough to forecast. In Southern Ontario, lake effect snow typically hits areas to the east of Lake Huron and Georgian Bay, but it can also impact communities to the north of both Lake Erie and Lake Ontario.

*Surface Temperature of Lake Huron throughout 2025 plotted with the 30 year average. Courtesy of* *NOAA CoastWatch*.

So how does a hotter-than-average summer impact lake effect snow? To put it simply, a warmer summer leads to warmer lakes. Looking at Lake Huron, the main source of lake effect snow in Southern Ontario, the surface water temperature is approximately 2°C warmer than the 30 year average.

One of the important properties of water is its high heat capacity, which means that lakes heat and cool slower than the surrounding land. The warmer lakes will take longer to freeze, meaning that the lake effect snow machine can run even longer.

The current surface temperatures across the Great Lakes are very similar to last year at the same time. Many will remember last fall when the Muskoka Region was buried after several days of intense lake effect snow, trapping people in their homes and cars after the highways were closed.

This trend continued through most of the winter due to large expanses of open water remaining present in the Lakes. This was particularly the case in Bruce, Grey, and Huron Counties, where consistent lake effect snow resulted in massive snow piles and drifts that were up to 12 feet tall! The amount of snow also had an effect on local schools, with more than 30 snow days announced for students of some school boards.

*Surface temperatures of the Great Lakes as of October 7th, 2025. Courtesy of* *Noaa Coastwatch*.

*Surface temperatures of the Great Lakes as of October 6th, 2024. Courtesy of* *NOAA Coastwatch*.

While it is still too early to predict exactly how much snow will fall and where over the coming months, it is looking likely that we can expect a considerable amount of lake effect snow like last year.

June 03, 2025

💨 WINDY WEDNESDAY: Environment Canada Forecasting Severe Thunderstorms With 90km/h Wind Gusts, Toonie Sized Hail & 50mm Flooding

June 03, 2025/ Adam Skinner

Environment Canada has released its latest Thunderstorm Outlook forecasting a “moderate” (2 out of 4) risk for severe thunderstorms across much of Southern Ontario on Wednesday, June 4th, 2025. They mention the potential for 90km/h damaging wind gusts, up to toonie size hail (2-3cm) and 50mm of rainfall that could bring isolated flooding. Timing looks to be from the afternoon to the evening for the strongest storms. Additionally, they mention a “minor” risk (1 out of 4) for thunderstorm activity on Thursday. We’ll break it down below.

💨 Windy Wednesday

Wednesday Morning:

The first storms are expected to arrive overnight Tuesday into Wednesday morning. These will mainly affecting portions of northeastern Ontario. This includes areas north of Sault Ste. Marie, stretching around Timmins and Moosonee towards the Quebec border and regions north of Lake Superior. Expect non-severe thunderstorms, with the main concern being isolated lightning strikes. While widespread heavy rain isn't the primary threat here, local rainfall amounts could reach up to 30 mm, with peak hourly rates around 15 mm. Environment Canada indicates a moderate confidence level for these initial storms.

Wednesday Afternoon and Evening:

The afternoon and evening will bring a risk for severe thunderstorms across much of Southern Ontario. This area could experience isolated storms capable of producing a combination of strong winds, large hail, and heavy rain. Impacts could include damage to plants and crops, and loose objects could be tossed around by the gusty winds. There's also a risk of damage to weaker structures, broken tree branches and even downed trees. With the heavy rain, possible flash flooding and water pooling on roads are also concerns. Rainfall in these stronger storms could locally total up to 50mm, with intense peak hourly rates reaching up to 30mm. It's important to note that areas experiencing several rounds of thunderstorms have the strongest chance of seeing isolated flooding.

Interestingly, Environment Canada adds a caveat for these Southern Ontario storms: while some thunderstorms may indeed produce very gusty winds, hail, and torrential downpours, there's a possibility that smoke aloft might hinder their overall strength. This makes Environment Canada’s confidence of how severe these storms will become lower than normal for this type of setup, despite the potential for “moderate” to “high” impacts.

⛈️ Thunder Thursday

Thursday:

The likelihood of thunderstorms continues into Thursday across many parts of northern, far northern, and southern Ontario including areas like Windsor, London, Toronto, Hamilton, etc. Non-severe thunderstorms remain possible. Once again, isolated lightning strikes will be the main concern with local rainfall generally expected to be less than 15 mm. Environment Canada has moderate confidence in these storms developing.

The focus Thursday shifts towards Eastern Ontario, highlighted as 'Area A' on the forecast map above. This area includes Ottawa, Cornwall, Perth, Brockville and areas east of Kingston. Stronger thunderstorms are possible, bringing hazards of strong winds and hail. If these storms strengthen as expected, they could damage plants and crops and toss loose objects. Environment Canada suggests these storms could produce wind gusts from 70-90 km/h and hail up to 2 cm (nickel size). Additionally, local rainfall amounts are expected to be up to 15 mm.

🔎 Staying Safe and Prepared

As we move into summer and a more active weather pattern, it’s critical to stay informed! To keep a close eye on our latest forecasts and get notified of any alerts, download our free app Instant Weather, available on Apple and Android devices.

Remember the golden rule of lightning safety: "When thunder roars, go indoors!" as there is no safe place outside during a thunderstorm. Ahead of the storms, particularly on Wednesday afternoon and evening in Southern Ontario and throughout Thursday in Eastern Ontario, take a moment to secure any loose outdoor items before the storms arrive. Things like patio furniture, trampolines, and garbage cans can become projectiles in strong winds.

If you're planning to be on the roads, be prepared for challenging driving conditions such as sudden downpours, significantly reduced visibility, and the possibility of water pooling on roadways, especially in areas expecting heavier rainfall.

Stay safe everyone and if it’s safe to do so, share your reports with half a million community members on our Facebook group called Ontario Storm Reports!

April 26, 2025

🌪️ ‘Tornado Tuesday’: Confidence Continues to Build For Significant Severe Thunderstorms Next Week in Ontario ⛈️

April 26, 2025/ Adam Skinner

TUESDAY, APRIL 29, 2025: Confidence continues to build for the risk of significant severe thunderstorms and tornado activity this Tuesday. Since our first article posted on Friday morning where we discussed this potential, we’ve continued to carefully monitor a strengthening trend on the forecast models. And at this point, we’re trending up from what initially looked like an Enhanced Risk (3/5), towards an isolated Significant Risk (4/5) based on the latest data. What we’re expecting at this point is isolated strong-to-significant severe thunderstorms across parts of Southwestern and Central Ontario Tuesday afternoon & evening that could possibly extend into the GTHA and parts of Eastern Ontario overnight, depending on the timing and speed of the cold front.

A lot can still change four days out but the consistency of the model data is why we here at InstantWeather have been discussing this for several days and why even Environment Canada has issued a preliminary forecast map today, discussing some of the risks on Tuesday including 100km/h damaging wind gusts and 2-4cm hail as you can see in the image below.

Environment Canada, in their first forecast map for this event has not mentioned a tornado risk. This is likely because we’re four days out but based on the data that we’ll be reviewing below, we’d be very surprised if they did not add a tornado risk in their forecast update tomorrow. Along with this forecast map, they wrote:

”A cold front will track east across northeastern and southern Ontario. By the afternoon, severe thunderstorms may develop with the main threats being strong wind gusts and large hail.”

🔎Model Data Review

In the image above, we’re looking at the latest “NAM” model data for 5pm on Tuesday and what we’re reviewing is the “Supercell Index”. This gives us an idea of how potent the environment is for rotating storms, which can lead to damaging wind gusts, large hail, flooding, intense lightning and in some cases, tornadoes. In our previous article, we only saw an orange supercell risk which is roughly an “Enhanced” risk level (3/5). However, in the latest data we are now seeing the colour red, which is hinting at the potential for a “Significant” risk level (4/5).

And in the image below, we see what the “Supercell Index” looks like at 8pm from the same “NAM” model, continuing the strong environment into the evening hours and extending it further into Eastern Ontario.

It’s still quite early but we’re now finally getting some higher quality data from the NAM model at 12km resolution and what you’re seeing above is simulated or “Future Radar” of how the event might play out. It’s still quite early and this could certainly change but it’s interesting to watch it evolve day-by-day. With this model run, the storms start to develop on the Lake Huron shoreline near the Kincardine and Goderich areas around 5pm. We do see some development up by Britt as well around that time. Again, this is just estimated and we could see a new solution to how this plays out each and every day leading up to Tuesday.

By 8pm in the image above, the simulated NAM future radar is suggesting we could see several potent supercells tracking through parts of Southwestern and Central Ontario. In previous model runs, we have seen a large line of storms as well, which in some cases can limit the tornado risk. Although, we could end up dealing with multi-cell supercells with an environment this strong and those can most certainly produce strong, isolated tornadoes.

And in this potential scenario from the NAM model, we still the storms expanding and tracking through deep Southwestern Ontario, Central Ontario and perhaps into parts of Eastern Ontario by 11pm. Typically, the later in the evening we get, the less we daytime heating we have to increase the severity of these storms but with how strong this environment is, it could be a late night for many of us and we’ll certainly be livestreaming as long as it takes to ensure everyone stays informed and safe.

If you’d like to get notified when we start livestreaming, subscribe to our YouTube channel for free and hit the bell icon to get notified when we go live.

And to get notified of any rotation detected, funnel cloud reports, tornado reports and Environment Canada watches & warnings, download our free mobile app InstantWeather on your phone or tablet.

🤔Final Thoughts:

If this trend continues and this system does not decide to weaken all of the sudden (here’s hoping it does), Tuesday continues to look like a strong or potentially significant severe thunderstorm risk. All modes of severe weather could be on the table with damaging wind gusts, torrential rain, isolated flooding, large hail, intense lightning and the potential for isolated tornadoes, some of which could be strong. Here’s hoping that it weakens into a marginal risk or vanishes all together!

Having said that, please begin to review your storm safety plan and start discussing the potential for rescheduling your Tuesday afternoon/evening plans.

More details ASAP.

Disclaimer: By using our services and any associated content, this means you implicitly agree to use the services and data available as is with no warranty issued or implied and should be used for informational purposes only. Any use of this data for decision making processes is done at the sole risk of the end user. Do not reproduce or disseminate our forecasts and content without explicit consent of Instant Weather, Inc.

April 25, 2025

🌪️ ‘Tornado Tuesday’ Might Make a Return in Southern Ontario Next Week ⛈️

April 25, 2025/ Adam Skinner

TUESDAY, APRIL 29, 2025: As I write this discussion (2am on Friday, April 25th, 2025), we’re quite a few days away from Tuesday, April 29th, 2025. Having said that, I’ve been carefully monitoring this strengthening trend on the forecast models for several days now and seeing them consistently suggesting an enhanced risk (3/5) for severe thunderstorms across much of Southern Ontario with the potential for isolated tornado activity. From Windsor, up through Barrie and perhaps even reaching parts of Eastern Ontario and the GTHA.

Typically, five days out is a lifetime for forecasting severe weather. Having said that, in rare circumstances you can see these strong environments coming from a mile away and this looks like this could be one of those events. Especially when we have a lot of data supporting the risk, which we’ll discuss further down the page.

Could this all change? You betcha. After more than a decade of forecasting severe weather in Ontario and across Canada, I’m no stranger to the potential for a “bust”. I could write this article and the entire system could vanish from the weather models. Tuesday could end up being just another typical spring day. Here’s hoping that’s the case. If, however, that is not the case and the trends we’re seeing in the models are correct, this is the type of event that requires getting the word out well in advance so that alternative plans can be considered and you can review your safety plan with your loved ones.

FRIDAY, APRIL 25, 2025: I should probably mention that we will have a risk for isolated thunderstorms today (Friday) and there is a marginal (low) risk for severe storms in deep southwestern Ontario later this afternoon and into the evening hours. Briefly severe hail and strong wind gusts are possible. At this point, it doesn’t look particularly intense but we’ll be keeping a close eye on it, nonetheless.

🔎Reviewing Models & Available Data For Tuesday

Typically, we like to compare the data from several different model systems. In this case, we’ll compare the American model, the European model and our own Canadian model. In the image above, we’re looking at the American model and what we’re reviewing is the severe weather “energy” that the storms are going to have available to them. The highest levels reaching almost 2,500 (in yellow/orange), which puts this event in the ‘Enhanced 3/5’ category, in my personal opinion.

For context, we can have marginal severe weather with energy levels as low as 500. And on the high-end, CAPE can reach as high as 5,000+ in the most extreme cases. So we’re somewhere in the middle, with totals potentially reaching greater than 1,000 and less than 3,000, at least, at this point.

Above is the Euro model, showing similar strong values to the American model in the deep southwest at 2pm. But, as you’ll see below, the energy progresses further east as we approach 5pm on Tuesday.

Above, we’ve got the 5pm timeframe from the Euro model. Showing organized energy values in place for the expected thunderstorms in the afternoon and evening hours.

While we’re taking a look at the European model, one interesting product they have is an estimated lightning density over several hours. As you can see in red, orange yellow and blue, quite a lot of thunderstorms are expected throughout the afternoon and into the evening hours, taking advantage of all that storm energy we discussed previously.

Below, let’s take a look at the Canadian energy for Tuesday. For some reason, the data looks really blocky. Not sure why PivotalWeather.com (the model provider we’re using for these images) is processing the Canadian model this way but perhaps, it’s coming that way directly from Environment Canada.

Regardless, a similar trend is showing up on the Canadian model that we’re seeing on both the European and American models. And with that, we have what is considered “model agreement”. And it’s not just these three models, other forecasting products called ‘Ensembles’ have 30+ model members and the vast majority are showing a strong severe thunderstorm risk for Tuesday.

This Canadian model image above is for 2pm on Tuesday. And similar to the European model data where we showed two separate timestamps (2pm and 5pm), this energy will push east, through the Barrie area and potentially into the GTHA and parts of Eastern Ontario through the afternoon and evening hours. Energy values look similar to the other two models, supporting the potential for an Enhanced Risk of severe thunderstorms.

Some other data worth noting in the image below is from the Storm Prediction Center (SPC) in Norman, Oklahoma. Not surprisingly, they are already showing a risk map for Tuesday, which they typically only show this far out when there is a strong system expected and a lot of agreement within the weather models.

You can see that southwestern Ontario gets highlighted in this risk area from Windsor, through Chatham-Kent and Sarnia, cutting off just shy of London. Having said that, the SPC’s only job is to forecast for the US. And as we’ve seen historically with them over the past decade, if they’re showing an extended range forecast that highlights parts of Southern Ontario, we could be in for quite the storm system much further into the Province than is shown below.

And in the final image below, we’re looking at a Machine Learning (AI) based severe weather estimation from the US. In this case, they cut off the data at the international border but by simply using your imagination, it’s clear that Southern Ontario is included in this risk region.

🤔Final Thoughts:

If these trends continue and this system does not decide to vanish from all the models suddenly (here’s hoping it does), Tuesday is shaping up to be a strong or potentially significant severe thunderstorm risk. All modes of severe weather could be on the table with damaging wind gusts, torrential rain, isolated flooding, large hail, intense lightning and the potential for isolated tornadoes, some of which could be strong. Here’s hoping that it weakens into a marginal risk or vanishes all together!

Having said that, now would be a good time to start reviewing your storm safety plan and discussing your plans for Tuesday if this system does decide to show up and affect Southern Ontario.

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Back-to-Back Clippers To Deliver Up to 20cm of Snow Across Southern Ontario by Wednesday

Nasty Winter Storm Will Bring Mixed Bag of Precipitation, Flash Freeze Risk, and Strong Winds to Alberta Monday & Tuesday

Short Blast of Snow Behind a Cold Front Will End the Week with 5-15cm of Snow for Parts of Alberta

Brief, Intense Snow Squalls Return to Southern Ontario’s Snowbelt on Thursday With Up to 20 to 50cm Expected

Yet More Snow on the Way for Southern Ontario With a Snowy System on Sunday Bringing Up to 10-20cm

BIG CHANGES Coming to Environment Canada’s Alerts Beginning Today

Headline Changes

NEW COLOURS

Impact Level

Confidence Level

Why These Changes Matter

Dangerous Snow Squalls Target Southern Ontario’s Snowbelt Starting Thursday With Up to 75cm of Snow Possible

Widespread 5–15cm of Fresh Snow to Blanket the Southern Prairies Early This Week

Snow Squalls Take Aim at London, Barrie and Northern GTA on Sunday With Up to 25-50cm of Snow Possible

Snow Squalls Could Bury Parts of Southern Ontario’s Snowbelt in Up to 50cm of Snow Early This Week

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Southern Ontario to Plunge Into Winter as Sunday Snowstorm Could Dump Up to 20 cm of Snow

Snowy Scare: Frightful Flurries May Haunt Parts of Southern Ontario on Halloween Night

Southern Ontario Turns Chilly With a Chance of Early Season Flurries for Some Areas Friday Morning

STORMY SUNDAY: Parts of Ontario Could Experience Damaging Wind Gusts & Flooding Risk This Weekend

💨 Southern Ontario

🌧️Northeastern Ontario

🔎 Staying Safe and Prepared

Get Your Shovels Ready: Ontario's Snowbelt Could Be Buried Again This Winter

💨 WINDY WEDNESDAY: Environment Canada Forecasting Severe Thunderstorms With 90km/h Wind Gusts, Toonie Sized Hail & 50mm Flooding

💨 Windy Wednesday

⛈️ Thunder Thursday

🔎 Staying Safe and Prepared

🌪️ ‘Tornado Tuesday’: Confidence Continues to Build For Significant Severe Thunderstorms Next Week in Ontario ⛈️

🔎Model Data Review

🤔Final Thoughts:

🌪️ ‘Tornado Tuesday’ Might Make a Return in Southern Ontario Next Week ⛈️

🔎Reviewing Models & Available Data For Tuesday

🤔Final Thoughts:

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