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A strong Alberta clipper is expected to track across Southern Ontario overnight and into Wednesday. This system will bring a widespread area of heavy snowfall along with pockets of blowing snow that may significantly reduce visibility during the morning and afternoon hours.

Environment Canada has issued broad snowfall warnings ahead of the system, highlighting the potential for hazardous travel conditions throughout the day. With the most intense snowfall expected during the key morning commute window, many school boards, especially in rural regions, are likely to consider cancelling buses for Wednesday.

The highest confidence for a snow day lies across the Parry Sound and West Parry Sound regions within the Near North District School Board, along with Peterborough County under the Kawartha Pine Ridge District School Board and all regions covered by Tri-Board Student Transportation Services. These school boards have a well-established track record of cancelling when Environment Canada issues any form of winter weather warning. Because of this, we have assigned them a 90 percent chance of bus cancellations.

A large swath of Southwestern, Central and Eastern Ontario follows closely behind with a 75 percent chance of a snow day. This includes the Greater Essex County District School Board, all of the Lambton Kent District School Board, Middlesex County within the Thames Valley District School Board and both Huron and Perth counties under the Avon Maitland District School Board.

It also includes the full Bluewater District School Board, Wellington and Dufferin under the Upper Grand District School Board, Simcoe West and Simcoe North within the Simcoe County District School Board, all of the Trillium Lakelands District School Board, Northumberland County for KPR, and the full Renfrew County and Upper Canada District School Boards.

We expect most of these boards to cancel buses, although there remains a small possibility that a few may choose to operate. Snowfall amounts of 10 to 20 cm sit right on the line where some boards become hesitant, and this season, we have seen several take a stricter approach to cancellations. That uncertainty keeps this group slightly below the 90 percent tier.

For many of the province’s more urban school boards, the picture becomes less clear. These include Ottawa under the Ottawa Student Transportation Authority, Barrie and surrounding communities within Simcoe Central and Simcoe South, northern portions of the Durham District School Board, Guelph within the Upper Grand District School Board, northern Halton under Halton Student Transportation, Waterloo under Student Transportation Services of Waterloo Region, and parts of the Thames Valley District School Board covering Oxford County, Elgin County and the City of London.

Urban boards tend to require closer to 15-20 cm of snow on the ground before cancelling, and the clipper’s expected totals may fall just shy of that threshold in some neighbourhoods. Because of this, we expect roughly half of these boards to cancel and half to continue running.

For the Greater Toronto Area, confidence drops even further. Environment Canada has opted to issue a special weather statement rather than a snowfall warning, and the potential for mixing may limit totals during the morning commute. These boards, including Durham South, York Region, Toronto, Peel Region, southern Halton and Hamilton, along with Niagara, tend to be the strictest in the province when it comes to cancellations due to their lower reliance on bused students.

Here, the chance of a snow day ranges from around 10 percent in Toronto to up to 25 percent in the surrounding boards. Surprise cancellations are not impossible, but the overall lean is toward buses running.

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.