Enter your city, ZIP code, or Canadian postal code below to check tonight’s snow day chance. Choose your school type, public, private, K–12, or college and university, since each closes under different conditions.Will School Be Closed Tomorrow? SnowDay Predictor and Calculator
Snow Day Predictor Ontario: Chances by City
Type your city or postal code into the tool above for an instant result for supported Ontario cities and postal codes. Ontario is a genuinely hard province to give a single answer for: Ottawa sits in a valley with its own microclimate, Southern Ontario's Georgian Bay and Lake Huron shoreline gets narrow, intense lake-effect squalls, and even school boards a short drive apart, like Halton's Oakville schools versus a neighbouring board, can reach different transportation decisions from the same storm.
Ottawa: A Valley With Its Own Weather
Student transportation in Ottawa is managed by the Ottawa Student Transportation Authority (OSTA) , which coordinates busing for both the Ottawa-Carleton District School Board (OCDSB) and the Ottawa Catholic School Board (OCSB) across 227 schools. OSTA's own published process reviews forecasts and current weather patterns starting around 4:00 a.m., makes its cancellation decision by 5:30 a.m., and aims to have that decision posted publicly by 6:15 a.m. OSTA's policy also explains that “the Ottawa Region is nestled in a valley, creating unique weather patterns,” so one nearby region can be in the middle of a winter storm while Ottawa itself stays clear, or vice versa. The decision weighs temperature, wind speed, road surface conditions, and visibility, not snowfall total alone.
Real events back this up. On February 16, 2016, Ottawa recorded a single-day snowfall record of 51.2 centimetres at the Ottawa International Airport, according to CBC News reporting citing Environment Canada, and most area school buses stayed cancelled for a second straight day while cleanup continued. In February 2025, OSTA cancelled all buses again during a major storm, with the city noting it would take longer than usual to clear the transportation network, according to CBC News .
Oakville and Halton Region: A Zone-Based System
Oakville's school transportation is handled by Halton Student Transportation Services (HSTS) , which serves roughly 31,500 students across the Halton District School Board (HDSB) and Halton Catholic District School Board (HCDSB), covering Oakville, Burlington, Milton, Georgetown, and Acton. The region is split into three inclement-weather zones, Zone 1 (Burlington and Oakville), Zone 2 (Milton), and Zone 3 (Georgetown and Acton), and a cancellation in one zone does not automatically apply to the others. Decisions are typically communicated by 6:30 a.m.
Halton also illustrates a distinction worth understanding anywhere in Ontario: a transportation cancellation and a school closure are not the same thing. HDSB and HCDSB have, in real documented cases, kept schools open for in-person learning while still cancelling bus service in one or more zones, meaning families who can get to school safely still attend, while bused students stay home. Always check both the transportation status and the school status separately, not just one or the other.
Barrie, Owen Sound, and the Georgian Bay Snowbelt
Communities along Georgian Bay and the Bruce Peninsula see some of the most localized winter weather in Southern Ontario. Bus transportation for the Barrie area is coordinated by the Simcoe County Student Transportation Consortium (SCSTC) , which divides Simcoe County into four weather zones, North (Elmvale, Midland, Penetanguishene, Orillia), South (Alliston, Beeton, Bradford, Cookstown, Tottenham), Central (Barrie, Innisfil, Angus), and West (Collingwood, Stayner, Wasaga Beach), and reviews conditions on a roughly 5:30 a.m. call before posting cancellations, generally between 6:00 and 6:30 a.m. On inclement weather days when only buses are cancelled, schools normally remain open for in-person learning. Owen Sound's transportation is coordinated separately by the Student Transportation Service Consortium of Grey Bruce , serving the Bluewater District School Board and Bruce-Grey Catholic District School Board.
In late November 2025, an Environment Canada snow squall warning brought 30 to 60 centimetres of snow to parts of Simcoe County, triggering widespread school bus cancellations in Barrie, Innisfil, Elmvale, Midland, and Penetanguishene, according to CP24 . Bus service was cancelled in Owen Sound and other parts of Grey County the same week, according to CTV News , while towns only a short drive away saw far less snowfall, a direct illustration of how narrow lake-effect squall bands can be. See our full lake-effect events page for more documented examples.
Want to See It on a Map?
Table: Ontario Coverage So Far (Confirmed Cities Only)
| City / Region | School board(s) / authority | What's confirmed |
|---|---|---|
| Ottawa | OCDSB, OCSB (via OSTA) | Valley microclimate; real 2016 record snowfall and 2025 storm events; decision by 5:30 a.m., posted by 6:15 a.m. |
| Oakville / Burlington / Milton / Halton Hills | HDSB, HCDSB (via HSTS) | Three-zone system; bus-cancelled-vs-school-open distinction; 6:30 a.m. decision time |
| Barrie / Innisfil | SCSTC (Simcoe County) | Nov 2025 squall event; named zone system; 5:30 a.m. call, 6:00–6:30 a.m. posting |
| Owen Sound | Student Transportation Service Consortium of Grey Bruce | Nov 2025 squall event, confirmed via CTV News; named authority identified |
| Collingwood / Midland / Penetanguishene | SCSTC (Simcoe County) | Nov 2025 squall event, confirmed via CP24; part of SCSTC's North and West zones |
Does the snow day predictor work for Ontario?
Yes, for supported Ontario cities and postal codes. The tool reflects live Open-Meteo forecast data plus, where confirmed, real school board transportation policy for that specific area.
Why did my nearby Ontario school stay open when another one closed?
Ontario school boards and transportation authorities make independent decisions, often organized by zone. Halton Student Transportation Services, for example, splits Oakville, Burlington, Milton, and Georgetown into three separate weather zones, so a cancellation in one zone does not automatically apply to the others. Localized lake-effect squalls near Georgian Bay can also drop heavy snow on one community while a town a short drive away sees very little.
Why are Ontario bus cancellations decided by zone?
Weather conditions can vary significantly within one county or region, so most Ontario transportation authorities divide their service area into zones and make a separate call for each. Simcoe County's transportation consortium, for example, uses four zones (North, South, Central, and West), and Halton uses three, so a single storm can cancel buses in one zone while another nearby zone runs normally.
Is a bus cancellation the same as a school closure in Ontario?
Not always. Some Ontario school boards, including Halton District School Board and Halton Catholic District School Board, have kept schools open for in-person learning while still cancelling bus transportation in one or more zones. Always check both statuses separately.
What time do Ontario school boards usually announce closures?
It varies by authority. Ottawa's OSTA makes its decision by 5:30 a.m. and aims to post it publicly by 6:15 a.m. Halton's HSTS typically communicates by 6:30 a.m. Simcoe County's transportation consortium holds its assessment call around 5:30 a.m. and generally posts between 6:00 and 6:30 a.m. Always confirm through your specific board or consortium's official channels, since timing is not standardized province-wide.
●Ottawa Student Transportation Authority, inclement weather policy and decision timeline
●Ottawa-Carleton District School Board, transportation and cancellation posting time
●CBC News, “Ottawa snowstorm cleanup still causing delays and cancellations the day after,” February 2016
●CBC News, “Buses pulled, parking banned, schools closed as region braces for major snowstorm,” February 2025
●Halton District School Board, “Bus Cancellations & School Closures”
●Simcoe County District School Board, transportation and SCSTC decision process
●Student Transportation Service Consortium of Grey Bruce, bus cancellations and school closures policy
●CP24, “Snow squalls force widespread school bus cancellations in Simcoe County,” November 2025
●CTV News, “Whiteout conditions force school bus cancellations in Grey County,” November 2025
●Environment and Climate Change Canada (regional forecast data referenced throughout)
Related reading: See more state and province closure guides, and browse famous lake-effect snow events across Southern Ontario. Check your own city with the SnowDay Score predictor.
Ready to check your own city? Try the live SnowDay Score predictor on the homepage for a real-time closure probability.
Explore More Snow Day Predictors
SnowDay Score covers school closure predictions across multiple regions. Check the forecast for another city:
Duluth, MN | Anoka-Hennepin, MN | Fairfax County, VA | Marquette, MI
Or return to the SnowDay Score homepage to check any supported city or postal code.
Ready to check your own city? Try the live SnowDay Score predictor above, or browse our other supported cities for tomorrow's closure odds.