Ottawa Snow Day Predictor OCDSB OCSB & CECCE Closures 2026

Ottawa Snow Day Predictor — Live School Closure Forecast for OCDSB, OCSB, CECCE and CEPEO

The Ottawa snow day predictor gives you a percentage chance that Ottawa schools will close, updated every hour using real Ottawa Valley weather data and past closure records. Ottawa gets about 235 centimetres of snow a year, more than almost any other big Canadian city, so this forecast helps families plan the morning before the four school boards make an official call.

Use the tool above by typing in “Ottawa” or your postal code. A postal code gives a more exact score if you live outside the downtown core.

Ottawa’s Four School Boards Each Decide Closures on Their Own

Ottawa has four school boards, and each one makes its own closure decision, so they do not always match. Here is how each board usually behaves during a storm.

When does OCDSB announce closures?

OCDSB, the largest English public board in Ottawa, usually announces a closure between 5:30 AM and 6:00 AM. You will see it on the OCDSB website, in a SchoolMessenger alert, and on Newstalk 580 CFRA.

Does OCSB follow OCDSB’s decision?

OCSB usually follows OCDSB within fifteen to thirty minutes, because both boards share many of the same bus routes across the city.

Do CECCE and CEPEO always close with the English boards?

No. CECCE and CEPEO, Ottawa’s French-language boards, make their own separate calls. Sometimes they close when English boards stay open, and sometimes the opposite happens. Families with kids in French school should check both board websites on their own.

Why Ottawa Closes Schools More Often Than Toronto

Ottawa closes schools more often than Toronto because it sits in the Ottawa Valley, a path for cold Arctic air, and gets roughly double Toronto’s snowfall with no large lake nearby to soften the cold.

Wind chill in Ottawa often drops below minus thirty degrees Celsius during the coldest weeks. Toronto sits next to Lake Ontario, which keeps its air milder. Ottawa also has large rural areas, and rural bus routes take longer to clear after snow falls, which stretches out how long a closure risk lasts.

Storm Types Behind Ottawa’s School Closures

Four storm types drive most Ottawa closures: Alberta Clippers, Colorado Lows, St. Lawrence snowbands, and freezing rain. Each one behaves differently, which is why the forecast score can shift fast.

What is an Alberta Clipper?

An Alberta Clipper is a fast storm from the Prairies that can drop ten to twenty centimetres of snow in just a few hours, often with extreme wind chill. Because it moves so fast, forecasters have a hard time predicting it more than twelve hours ahead.

What is a Colorado Low?

A Colorado Low is a slow-moving storm that can drop more than thirty centimetres of snow over one to two days. It is responsible for more multi-day school closures in Ottawa than any other storm type.

What is a St. Lawrence snowband?

A St. Lawrence snowband forms when moisture off the St. Lawrence River meets cold air, creating a narrow but intense strip of snow, usually hitting areas east of Ottawa like Orleans and Cumberland hardest.

Why is freezing rain the most dangerous event?

Freezing rain is the most dangerous event because just five millimetres of ice can close all four boards at once. It forms when a layer of warm air sits above a cold layer near the ground, and it makes bus travel far riskier than fresh snow does.

Weather Conditions That Usually Trigger a Closure

Ottawa schools most often close after fifteen to twenty centimetres of overnight snow, wind chill below minus thirty degrees, or any freezing rain on the roads. Here is how each factor plays a role, based on past OCDSB decisions.

• Snowfall of 15–20 cm overnight is the single most common trigger. Totals above 20 cm make a closure highly likely.
• Wind chill below minus 30 degrees at 6 AM raises closure odds even without any snow, since extreme cold puts kids waiting at bus stops at risk.
• Any freezing rain overnight pushes closure odds up sharply, because ice is unpredictable no matter how much snow has fallen.
• Storms arriving between midnight and 6 AM carry the highest risk, since road crews have less time to treat routes before buses leave around 6:30 AM.
• Rural routes near Greely, Richmond, and Metcalfe are judged separately from urban routes, so buses can be cancelled there while city schools stay open.

How to Read the Ottawa Forecast Score

The forecast score is a percentage chance of closure, built from live temperature, expected overnight snowfall, wind chill, and precipitation type, refreshed hourly from Environment and Climate Change Canada data. A score under 30% means a closure is unlikely. A score above 80% means conditions closely match past closure days.

Check the score the evening before a storm, then check again around 5:30 AM for the most accurate read before any board makes it official.



When Ottawa Closures Happen Most

January and February carry the highest closure risk in Ottawa, since Alberta Clippers peak during these months and average temperatures sit near minus ten degrees Celsius. December brings early heavy snow before road crews are fully ready, and March adds freezing rain risk as warmer air starts overriding cold ground.

This Tool Is a Planning Estimate, Not an Official Announcement

This forecast is a planning estimate and does not replace an official board announcement. OCDSB, OCSB, CECCE, and CEPEO are the only authorities that decide closures, so always confirm through your board’s own website or alert system before changing your morning plans.

For the full picture of how boards make this call across the province, see how Ontario school boards decide snow days. If you are checking conditions somewhere else in the province, the Ontario snow day predictor covers every city and board. Families outside Ottawa dealing with similarly heavy snowfall may also want to see the Sudbury weather and snow day guide.

Frequently Asked Questions About the Ottawa Snow Day Predictor

How does the Ottawa snow day predictor work?

It combines live Ottawa Valley weather with historical OCDSB and OCSB closure records to output an hourly percentage probability of closure.

When does OCDSB usually announce a closure?

Between 5:30 AM and 6:00 AM, through its website, SchoolMessenger, and 580 CFRA radio. OCSB usually follows within about thirty minutes.

Does Ottawa close schools more often than Toronto?

Yes. Ottawa averages about 235 cm of snow a year compared to roughly 115 cm in Toronto, and the Ottawa Valley exposes the city to more frequent severe storms.

What weather conditions typically close Ottawa schools?

Overnight snowfall of 15–20 cm, wind chill below minus 30 degrees, or any freezing rain accumulation are the main triggers.

Do all four Ottawa school boards close on the same day?

Not always. OCDSB and OCSB usually align, but CECCE and CEPEO decide independently and sometimes differ from the English boards.

What is an Alberta Clipper?

A fast-moving storm from the Prairies that brings sudden heavy snow and extreme wind chill, often with limited warning ahead of time.

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