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A snow day calculator built for Canada
Most snow day calculators are written for American districts, where the usual answer to a storm is a two-hour delay. Canadian mornings work differently. In Ontario, busing is usually run by a transportation consortium shared by the public and Catholic boards, and the most common snowy-day announcement is not “schools closed” but “buses cancelled” — often for one zone, while schools stay open for anyone who can get there.
So this version gives three outcomes: school closure, buses cancelled with schools open, and a normal day. It works in centimetres, millimetres, °C and km/h. You enter the forecast from Environment Canada or your local forecast; the page does not fetch live weather, alerts or closure announcements.
School closure vs bus cancellation
A bus cancellation is a transportation decision: drivers and consortium staff check rural roads before dawn and cancel routes that are unsafe. A closure is a board decision to close school buildings. The two are announced separately in most of Ontario, often by different organisations. The well-known exception among the cities people search for is Hamilton, where HWDSB’s published rule is that a weather bus cancellation closes its schools and offices too — choose Hamilton and the calculator counts the bus-cancellation chance as a closure. PEI works differently again: when the Public Schools Branch cannot decide by 6:30 a.m. it announces a one-hour delay.
Example: 12 cm of snow in 6 hours, still falling at bus time, −5 °C, 30 km/h wind gusting to 55 km/h, poor visibility and snow-covered roads. Where buses are cancelled separately that gives a 74% closure estimate and 21% for buses cancelled with schools open; with Hamilton’s rule the closure estimate becomes 95%.
On a bus-cancellation day the schools are usually open, so a student who stays home is normally marked absent — check your board’s rules. The attendance calculator shows how missed days change an attendance percentage.
Snow days by area
The area selector does not change the weather model. It sets the bus rule, the name of the middle outcome and who announces what. It is not a feed of today’s cancellations, so always check the links it gives.
As described when last checked in October 2026. Boards, districts and state rules can change from one winter to the next — always follow your own school’s announcement.
Toronto and the GTA (Toronto, Peel, York, Durham)
TDSB, TCDSB, Peel DSB, Dufferin-Peel CDSB, York Region DSB, York Catholic DSB, Durham DSB and Durham CDSB. Buses: each region’s student transportation service. Boards post decisions by about 6 to 6:15 a.m. TDSB says about 93% of its students do not ride a bus, so it often cancels buses while schools stay open; the boards describe full closures as rare and reserved for extreme conditions.
Milton, Oakville, Burlington, Halton Hills (Halton)
Halton DSB and Halton Catholic DSB. Buses: Halton Student Transportation Services. Halton is split into three weather zones (1: Burlington and Oakville, 2: Milton, 3: Georgetown and Acton). By 6:30 a.m. HDSB says whether transportation is cancelled and whether schools are closed; when buses are cancelled but schools stay open, in-person and e-learning courses continue.
Barrie, Orillia, Innisfil (Simcoe County)
Simcoe County DSB and Simcoe Muskoka Catholic DSB. Buses: Simcoe County Student Transportation Consortium. Buses are cancelled by zone (north, central, south), so Orillia buses can be off while Barrie buses run. When buses are cancelled, schools usually stay open. Lake-effect squalls off Georgian Bay make zone-by-zone days common.
Hamilton
Hamilton-Wentworth DSB and Hamilton-Wentworth Catholic DSB. Buses: Hamilton Wentworth Student Transportation Services. HWDSB’s published rule: when it cancels buses for severe weather, its schools and administrative buildings close too. It aims to announce by 6 a.m.
Waterloo Region (Waterloo, Kitchener, Cambridge)
Waterloo Region DSB and Waterloo Catholic DSB. Buses: Student Transportation Services of Waterloo Region. Bus cancellations are posted by the transportation service, usually before 7 a.m.; the boards publish school closures separately.
Brantford, Paris, Brant, Haldimand, Norfolk
Grand Erie DSB and Brant Haldimand Norfolk Catholic DSB. Buses: Student Transportation Services of Brant Haldimand Norfolk. Buses can be cancelled while schools stay open; in extreme weather the boards have also closed schools and all transportation together.
Ottawa
Ottawa-Carleton DSB and Ottawa Catholic School Board. Buses: Ottawa Student Transportation Authority (OSTA). When OSTA cancels transportation for weather it does so for all schools, and the OCDSB’s own notices say schools remain open. Cancellations are posted by about 6:15 a.m.
Peterborough, Northumberland, Clarington (STSCO)
Kawartha Pine Ridge DSB and Peterborough Victoria Northumberland and Clarington Catholic DSB. Buses: Student Transportation Services of Central Ontario (STSCO). STSCO can cancel buses for one area (for example Northumberland County) while buses run elsewhere, and its notices say schools remain open. A morning cancellation also cancels the afternoon run.
Greater Sudbury
Rainbow DSB, Sudbury Catholic DSB and the two French-language boards. Buses: Sudbury Student Services Consortium. The consortium says schools in the affected areas stay open when buses are cancelled, and that extreme cold (around −35 °C and colder) can delay or cancel buses because diesel vehicles may break down.
North Bay and Parry Sound
Near North DSB and Nipissing-Parry Sound Catholic DSB. Buses: Nipissing-Parry Sound Student Transportation Services. Buses are cancelled by weather zone. The Near North DSB says schools remain open when buses are cancelled, and a route cancelled in the morning does not run in the afternoon.
Halifax (Nova Scotia)
Halifax Regional Centre for Education (HRCE). Buses: HRCE transportation providers. HRCE aims to decide as close to 6 a.m. as possible. An announcement can be: schools open but some or all buses not running, some schools closed, or all schools closed.
Prince Edward Island
Public Schools Branch. Buses: Public Schools Branch. The Public Schools Branch aims to announce by 6:30 a.m.; if it cannot decide by then it announces a one-hour delay and follows up by 8:00 a.m. Partial closures and delays are announced by Family of Schools.
What drives a Canadian snow day
- Snow before and during the bus runs — place the storm on the timeline; snow still falling at bus time counts most.
- Freezing rain and drizzle — a thin glaze on rural roads is a classic reason for bus cancellations. The ice day calculator looks at ice on its own.
- Blowing snow and squalls — wind, gusts and low visibility count when snow or ice is falling.
- Extreme cold — Environment Canada rates a wind chill of −28 and colder as high risk, when exposed skin can freeze in 10 to 30 minutes. Some consortia cancel buses for extreme cold even without snow; the cold day calculator looks at this on its own.
How the estimate is made
Each factor you enter becomes points; the points combine into a weather pressure out of 100; an S-curve turns pressure into chances. Every weight is a heuristic assumption — not fitted to board records — and the full table is on the main snow day calculator. The working for your own result is under “See the full working”. Nothing is looked up — not your location and not the weather.
How accurate is it?
There is no validated accuracy figure for this model, so the page does not claim one. Borderline storms near 0 °C are the hardest, and consortia decide zone by zone on what drivers find on the roads at 5 a.m. Use your board’s and consortium’s announcements for the real answer.
Frequently asked questions
Is there a snow day calculator for Canada?
Yes — this page. Enter your forecast in centimetres, °C and km/h, choose your area, and read the chance of a school closure, of buses being cancelled while schools stay open, and of a normal day. It is free and needs no sign-up.
Does it read Environment Canada’s forecast?
No. This calculator uses the weather conditions you enter; it does not fetch live weather, alerts or closure announcements. Take the figures from Environment Canada’s forecast for your town and enter them.
Will there be a snow day tomorrow in Ontario?
Enter tomorrow’s forecast — snow before school, freezing rain, the morning temperature and wind — and choose your area. The estimate follows those figures. Your school board and your student transportation consortium make the real decisions, usually between 6 and 7 a.m.
What is the difference between a bus cancellation and a school closure?
In much of Ontario, buses are run by a transportation consortium shared by the public and Catholic boards. On a bad morning it can cancel buses for a zone while schools stay open. A school closure means the building is closed to students. Some boards, such as HWDSB in Hamilton, close schools whenever they cancel buses for weather.
If buses are cancelled, is my child marked absent?
Usually the school stays open on a bus-cancellation day, so a student who stays home is normally recorded as absent — check your board’s own attendance rules. The attendance calculator shows how missed days change an attendance percentage.
How much snow does it take to close schools in Canada?
There is no national figure, and closures of whole school buildings are less common than bus cancellations. Freezing rain, blowing snow on rural roads and extreme cold often matter more than the snowfall total.
Does this work for Toronto, Ottawa, Barrie, Hamilton or Sudbury?
Yes. Choose your area: each entry sets the local bus-cancellation rule and links to the board or consortium that makes the announcement. For anywhere else, choose “Elsewhere in Ontario” or “Elsewhere in Canada”.
How accurate is a Canadian snow day calculator?
No honest single figure exists. This page does not claim an accuracy percentage; it shows every factor and assumption so you can judge the estimate yourself.