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After a disruptive snowstorm delivered Toronto’s largest single-day snowfall on record on Sunday, students across much of the Golden Horseshoe and Eastern Ontario saw widespread school bus cancellations and even school closures on Monday. But for communities closer to Lake Huron and Georgian Bay, it marked a return to normal, with students finally heading back to school after being off for much of the previous week in some areas.

Now that the main storm system has moved out of the region, attention turns back to lake effect snow. Snow squall activity is expected to redevelop across Southern Ontario’s snowbelt, bringing with it the renewed potential for school bus cancellations on Tuesday.

Localized snow squalls are forecast to develop tonight across the Bruce Peninsula and then extend northeast of Georgian Bay into the Parry Sound region through Tuesday morning. As the day progresses, these squalls are expected to gradually shift south of the region, but not before producing periods of heavy snow and poor visibility during the morning hours.

With snow squall warnings in place from Environment Canada, highlighting the risk of significant snowfall and reduced visibility, there is a strong chance that some of the hardest hit regions will experience another snow day on Tuesday.

Our highest confidence is in the Parry Sound region under the Near North District School Board. This area is expected to see the most intense and persistent snow squall activity through the morning, making bus travel unsafe. As a result, we have assigned Parry Sound a 90 percent chance of school bus cancellations.

A strong likelihood follows closely behind, with a 75 percent chance assigned to the Bruce Peninsula within the Bluewater District School Board and East Parry Sound under the Near North District School Board. While the Bruce Peninsula is expected to see treacherous conditions, Bluewater has already experienced a high number of cancellations this season. Because of that, there remains a slight chance they may attempt to run buses if conditions are marginal early in the morning, keeping this region just below the highest tier.

Along the Lake Huron shoreline, including the remainder of Bruce County and extending into North Huron County under the Avon Maitland District School Board, we have assigned a 50 percent chance. Snowfall totals here are not expected to be extreme, but strong wind gusts of 50 to 60 km/h could lead to areas of blowing snow and rapidly changing visibility. These conditions could go either way depending on how exposed routes are early Tuesday morning.

Farther inland, confidence drops off. Perth County, under the Avon Maitland District School Board, and all of Grey County within the Bluewater District School Board have been given a 25 percent chance. Winds are expected to weaken farther from the lakes, and snowfall intensity should be lower, making cancellations less likely but not impossible.

East of Georgian Bay, North Muskoka, under the Trillium Lakelands District School Board, has been placed in the 50 percent category, as it currently sits under a snow squall warning. That said, TLDSB has a history of holding off on cancellations unless conditions are actively poor during the morning bus run, even when warnings are in effect. Because of that, confidence remains split. South Muskoka under TLDSB and North Bay within the Near North District School Board have been assigned a lower 25 percent chance.

Farther east, lake effect activity may also impact Northumberland County into the Belleville and Picton area. Environment Canada has issued a snow squall watch for this region from Tuesday morning into the evening. Because of that, we have given Belleville and Prince Edward County under Tri-Board Student Transportation Services a 50 percent chance of bus cancellations.

A 25 percent chance has also been assigned to Northumberland County under the Kawartha Pine Ridge District School Board, as well as Central Hastings, Central Lennox and Addington, and South Frontenac under Tri-Board. While it remains questionable whether conditions will be severe enough to prompt cancellations in these areas, these school boards tend to be more proactive when Environment Canada alerts are in place, which keeps the door open for possible decisions.

Elsewhere across Southern Ontario, the chance of a snow day on Tuesday is low to very low. Some regions that were hit hard by Sunday’s historic snowfall could still see lingering cleanup issues, but widespread cancellations for that reason appear unlikely.

In fact, the Toronto District School Board has already confirmed that schools will be open on Tuesday, despite Toronto being the hardest hit area from Sunday’s storm. With that in mind, it becomes increasingly questionable that other regions would cancel solely due to cleanup concerns if Toronto is able to reopen.

Disclaimer: Instant Weather has zero authority when it comes to bus and school closures.

It is completely up to the school boards, bus companies, local authorities, and parents to decide what is best for their children. This is our best guess based on our forecast.