Check your Toronto snow day probability before the school announcement. School closure prediction based on real local weather data.
Toronto ON • Greater Toronto Area • Lake Ontario Region
Toronto sits on the north shore of Lake Ontario in Southern Ontario, giving it a winter weather profile unlike any other major Canadian city. Snow accumulation matters — but freezing rain is Toronto’s signature winter hazard, capable of closing school boards across the entire GTA with just a few millimetres of ice. Our Snow Day Calculator pulls real-time Environment and Climate Change Canada forecast data for Toronto ON and the Greater Toronto Area, analyzing snowfall totals, freezing rain risk, temperature, wind chill, and road conditions to generate a school closure probability for your postal code.
The Toronto District School Board (TDSB) is Canada’s largest school board, serving over 240,000 students. The Toronto Catholic District School Board (TCDSB), York Region District School Board, Peel District School Board, and Durham District School Board all serve the broader GTA and each make independent closure decisions. Enter your postal code for a localized estimate — but the official call always comes from your board.
Lake Ontario rarely freezes completely, which means it supplies moisture to storm systems throughout the winter season. When cold northwest air flows across the lake, it picks up moisture and deposits it as lake-effect snow on Toronto’s eastern and northeastern neighbourhoods, as well as communities in Durham Region and the Oshawa area. These bands can be intense and localized, dropping 20 to 40 cm in a few hours on communities directly in their path while leaving the city centre with far less. The GTA’s school boards must weigh these uneven totals when making area-wide closure decisions.
More than any other winter hazard, freezing rain closes Toronto schools. When warm air overrides cold surface air, rain falls and freezes on contact with every surface — roads, sidewalks, bus stop poles, school steps. Even 3 to 5 mm of ice accumulation creates dangerous conditions citywide.
Cold air crossing Lake Ontario generates intense snow bands that can target Toronto\'s east end and communities in Durham and Northumberland. These events can dump 20 to 30 cm in hours while Etobicoke and Mississauga see only a light dusting.
Toronto sits in the path of major storm tracks from the US Midwest and the Gulf of Mexico. Large nor\'easter-type systems can bring 20 to 40 cm of snow to the entire GTA, overwhelming the city\'s snow removal capacity and producing multi-day closure situations.
Toronto\'s dense urban core — streetcar tracks, bike lanes, narrow residential streets, packed school zones — makes snow removal slow and uneven. Side streets and school walkways can remain hazardous long after main roads are cleared.
Toronto averages about 115 cm of snow per season, but the mix of precipitation types is what defines its winters. Snowfall, freezing rain, ice pellets, and rain can all fall in the same storm as temperatures fluctuate around the freezing mark. Toronto\'s 2013 ice storm left more than 300,000 homes without power and schools closed for days — a reminder that freezing rain events can be far more disruptive than heavy snowfall alone. School boards weigh all precipitation types, not just snow totals, when making closure decisions.
Moving students safely through Toronto in a winter storm is a massive logistical challenge. The TDSB and TCDSB together serve hundreds of thousands of students across a city of 2.9 million people. Student Transportation of Central Ontario (STCO) operates school bus routes across much of the GTA. When buses can\'t safely run their routes — due to unplowed streets, ice, or visibility — boards cancel school. The TTC\'s surface routes also slow significantly in heavy snow, affecting the large number of students who ride transit to school.
The TDSB, TCDSB, and other GTA boards monitor Environment Canada forecasts and road condition reports from the City of Toronto and regional municipalities through the night before a potential closure. Key factors: precipitation type (snow vs. freezing rain), accumulation, temperature at school start time, road clearing status, and bus transportation safety. The Student Transportation of Central Ontario team makes the bus call independently; boards often follow their recommendation. Most closures are announced before 6:00 AM.
Canada\'s largest school board with 240,000+ students. TDSB communicates closures via its website, CP24\'s school closing ticker, CBC/CTV/Global Toronto, 680 News radio, and the School Messenger app. Freezing rain decisions are often made earlier than snow-only decisions.
Serves 85,000+ Catholic students across Toronto. TCDSB makes independent decisions but often aligns with TDSB, particularly during city-wide freezing rain or major snow events. Announcements go through the same media channels.
York Region DSB serves Vaughan, Markham, and Richmond Hill. Peel DSB covers Mississauga and Brampton. Both make fully independent decisions. York Region\'s northern communities sometimes see more snow than the city; Peel\'s large geographic area means road conditions vary significantly across its jurisdiction.
Covers Pickering, Ajax, Whitby, and Oshawa to Toronto\'s east. Durham sits directly in the primary lake-effect corridor and often receives more snow than the city during northwest wind events, leading to independent closure decisions that differ from TDSB.
| Weather Factor | Low Impact | Moderate Impact | High Impact |
|---|---|---|---|
| Snow Accumulation | Under 5 cm | 5–15 cm | 15 cm+ (closure likely) |
| Freezing Rain | Trace amounts | 2–5 mm | 5 mm+ (closure very likely) |
| Temperature at 6 AM | Above -5°C | Below -20°C with wind chill | |
| Road Conditions | Clear and salted | Partially covered | Icy or unplowed side streets |
| Lake-Effect Alert | None | Lake-effect watch | Lake-effect warning active |
Environment Canada\'s forecast tells you how much snow or freezing rain is expected. The Snow Day Calculator translates that forecast — accounting for precipitation type, timing, temperature, and road conditions — into a school closure probability. In Toronto, 5 mm of forecasted freezing rain has a higher closure probability than 20 cm of fluffy snow on a cold, calm day with good road clearing. The calculator weighs all of these factors together.
In Toronto, a freezing rain warning from Environment Canada is often a stronger closure indicator than a snowfall warning. Our calculator weights freezing rain heavily in the probability score.
CP24 runs a live school closing ticker during winter storms. Most GTA boards announce before 6:00 AM. Run the calculator the night before to track rising probability.
Lake-effect snow can hit Durham Region with 30 cm while Etobicoke sees 5 cm. Use your postal code for the most accurate local prediction for your school board.
Our calculator covers Toronto and the Greater Toronto Area, including: Mississauga, Brampton, Vaughan, Markham, Richmond Hill, Scarborough, Etobicoke, and North York. Enter any GTA postal code for a localized snow day prediction.
Explore More Cities
Check snow day chances for cities near Toronto.