The chance snow, ice or cold cancels school buses in Ottawa on the next school morning, from the latest forecast
Loading the forecast for Ottawa…
An estimate from the forecast, not a promise.
Looks like a regular school day. Check again if the forecast changes.
🧪 Test weather, not the real forecast
In much of Canada, school buses can be cancelled while schools stay open. This is a weather estimate, not an official bus cancellation; check your school board or bus service.
Opens a web search in a new tab. Only your school board can say for sure.
Days 3–5 are an early outlook and may change. School holidays aren’t known.
7 am temperature: —
No snow or ice expected overnight
Overnight window: 6 pm – 8 am before school.
The calculator above is already set to Ottawa. It takes the hourly forecast for the city from 6 pm to 8 am before the next school morning and scores overnight snow, freezing rain, cold at 7 am and gusty wind, giving a chance from 1% to 99% in °C, cm and km/h. For the public board, a snow day means cancelled yellow school buses, decided early in the morning by the Ottawa Student Transportation Authority (OSTA). This page estimates the weather’s effect; it doesn’t know OSTA’s decision.
Local weather
Environment and Climate Change Canada’s 1981–2010 climate normals for Ottawa Macdonald-Cartier International Airport, about 10 km south of downtown, show:
| Average snowfall per year | 223.5 cm |
|---|---|
| Snowiest month | January, 53.9 cm |
| Days with 5 cm or more of snowfall | 15.1 a year |
| Coldest month (daily average) | January, −10.3°C |
| Days with a wind chill below −30 | 12.1 a year |
Ottawa’s yearly snowfall is close to Barrie’s and Halifax’s, but its January is several degrees colder (−10.3°C, against −7.7°C in Barrie and −5.9°C in Halifax in the same normals). The cold keeps snow on the ground: the airport averages 101.1 days a year with at least 5 cm of snow cover, more than twice Toronto’s 43.3. It also averages 47.4 days a year with a wind chill below −20 and 16.3 nights colder than −20°C. According to OCDSB, OSTA weighs the type of precipitation, how long it’s forecast to last, the amount and the air temperature, across its whole service area.
Who decides
The Ottawa Catholic School Board’s transportation page explains that the Ottawa Student Transportation Authority (OSTA) manages all home-to-school transportation for both English-language boards. French-language schools have their own boards.
The public board. Its snow day notice says OSTA decides between 4:00 and 5:30 a.m. when there is inclement weather, after monitoring the forecast every four hours, then contacts the board. On a snow day, yellow buses are cancelled, OC Transpo high school routes keep running and all schools remain open. Its notices say families may drop children off and pick them up at regular bell times.
The Catholic board. Its transportation page points families to OSTA for weather-related bus cancellations and recommends the OSTA app for notifications, since email updates are no longer sent. For whether its schools stay open, check OCSB’s own announcements.
Buses
This page predicts the weather, not official cancellations. Because cold mornings matter so much in Ottawa, the Cold & Ice Day Calculator is worth checking too: it scores wind chill at bus time, which the snow formula here doesn’t.
Method
The calculator applies the published snow day formula to the next school morning on Ottawa’s clock:
The result stays between 1% and 99%. The points are first estimates, not compared with real OSTA cancellations, so the accuracy is unknown. The points were first set for US school districts. For OCDSB, a snow day means cancelled buses while schools stay open, so read a high % as rough snow-day weather, not a sure closure.
FAQ
No one can say until OSTA decides, between 4:00 and 5:30 a.m. on a bad-weather morning. The calculator above estimates the chance from the latest forecast for Ottawa; check it the evening before and again early in the morning.
For the public board, yes: OCDSB says that on a snow day yellow buses are cancelled but all its schools remain open, and families may drop children off at regular bell times. OCSB families should check OCSB’s own announcements.
On the Ottawa Student Transportation Authority’s website after 6:15 am, in the OSTA app, on Twitter at @OttSchoolBus, and on local radio after 6:15 am.
According to OCDSB, on a snow day yellow bus service is cancelled but OC Transpo high school routes continue to operate. Check the day’s OCDSB notice for details.
About 224 cm a year on average (223.5 cm), with January the snowiest month at 53.9 cm, at Ottawa Macdonald-Cartier International Airport in Environment and Climate Change Canada’s 1981–2010 climate normals.
No. This site isn’t connected to OSTA, OCDSB, OCSB or any weather service. It gives an estimate; their announcements give the answer.