Ontario winter outlook
In Ontario, the far more common outcome is a bus cancellation rather than a school closure, and those are announced by different organisations. Run the calculator, then read how the system actually works here.
Live Ontario forecast estimate
Enter a location to compare tomorrow's snow, ice, temperature, wind and morning timing.
Regional pattern
A single province-wide snowfall figure rarely explains a school decision here. These are the patterns worth knowing before reading any Ontario forecast.
Southern Ontario's most disruptive winter weather often comes from squalls forming over Lake Huron and Georgian Bay when cold air crosses open water. Northwest flow drives these bands inland toward Grey-Bruce, Waterloo Region, London and occasionally the northwest edge of the Greater Toronto Area. Squalls are intense, narrow and fast: visibility can drop from clear to near zero within minutes, which is precisely the condition that stops buses.
Across most of Ontario, student transportation is operated by consortia serving several boards at once, and those consortia announce transportation cancellations by geographic zone. Schools very often remain open with staff on site while buses are cancelled. This is the single most important thing to understand about an Ontario forecast: a high weather-pressure morning usually means checking the consortium's zone status, not waiting for a full closure.
Systems tracking along the St. Lawrence and Ottawa valleys frequently deliver ice rather than snow. Cold air pooling in the valleys keeps surfaces below freezing while rain falls through a warmer layer aloft. Ottawa and eastern Ontario see this pattern more often than the southwest, and it disrupts transportation with very little measurable accumulation.
Lakes Ontario and Erie keep the immediate shoreline milder, which is why Windsor and Toronto often get slush or rain where inland communities get snow. Move away from the water and both overnight lows and wind chills become more severe. Northern Ontario is colder and snowier again, with extreme cold warnings a routine part of the season.
Permanent city pages
Each page loads its own coordinates, its own local closure factors and its own official sources. Any other Ontario community can be searched directly in the calculator above.
The percentage on this page is a weather-based planning estimate. It scores forecast snow and ice, temperature, wind chill, morning timing, broad area type and school level, and it shows each of those with its own value and published weight. It does not observe road treatment, staffing, building utilities or the judgement of the people who actually make the call. The methodology page documents every threshold and the accuracy and limitations page is explicit about the gaps.
No school system in Ontario publishes a snowfall number that triggers a closure, and this site does not invent one. Use the estimate to decide whether a backup plan is worth arranging, then let the official announcement decide what actually happens.
Primary weather and road-condition sources covering Ontario. School and transportation decisions come from individual school systems.
Ontario questions
No. Public, Catholic and French-language boards serving the same territory each decide independently, and the transportation consortium serving them decides separately again. It is entirely normal for a family with children in two systems to receive two different messages on the same morning.
Most often buses are cancelled while schools stay open, and those announcements come from the regional student transportation consortium by zone. A full board closure is a separate and less frequent decision. Always check both the consortium status and your board's notice.
It is one of Environment and Climate Change Canada's winter alert types, issued when bands of intense localised snow are expected to bring abrupt whiteouts and fast accumulation. Ontario transportation consortia take squalls seriously precisely because the hazard is the loss of visibility rather than the depth left behind.
The calculator loads five selectable days, so looking at a Monday or a Thursday is as easy as looking at tomorrow. Treat anything beyond roughly two days as pattern awareness rather than a school forecast, because squall positioning and precipitation type are still unsettled at that range.
Toronto, Ottawa, Hamilton, Kitchener, Waterloo, London and Windsor each have a dedicated page with local context. Any other Ontario community can be searched directly in the calculator by name or postal code.