Southern Alberta
In Calgary the hazard is usually ice created by a chinook thaw refreezing, or extreme cold, rather than snow depth. The estimate below is loaded with live Calgary forecast data.
Live Calgary forecast estimate
Enter a location to compare tomorrow's snow, ice, temperature, wind and morning timing.
Local conditions
Calgary sits on the western prairie at the foot of the Rockies, high enough and close enough to the mountains to experience frequent chinooks. These warm, dry downslope winds can raise temperatures dramatically within hours, melting snow and running water across pavement. When the wind eases or the temperature falls back, that water refreezes into sheet ice on residential streets, sidewalks and school walkways. Between chinooks, Arctic air can settle in for extended periods with severe wind chills, and the surrounding open prairie allows blowing snow to cut visibility on rural routes.
What actually drives a decision
This is Calgary's signature winter problem and it is not captured by a snowfall forecast at all. Watch for a mild day followed by a sharp overnight drop: the minimum temperature and the previous day's melt matter more than any accumulation figure. Side streets and walkways ice before arterial roads.
Prolonged Arctic outbreaks push wind chills to levels where waiting outdoors is genuinely unsafe, and cold also stops buses from starting. That mechanical constraint affects service independently of road conditions, and it is a common reason for route-level cancellations.
Calgary's public and Catholic divisions generally maintain operations through winter weather, so the practical outcome is usually a transportation cancellation or route change rather than a school closure. Check the division's transportation notices, which are updated early in the morning.
Outside the city, wind lifts existing snow across open country and reduces visibility to nothing with no new snowfall. Rural routes are cancelled for visibility far more often than for accumulation.
The forecast for the coordinates above is scored against six weighted factors: snow and ice, temperature, wind chill, morning timing, area and routes, and school level. Around Calgary the rows that most often carry the number are temperature, wind chill. Every factor appears in the result with its own value, score bar and published weight, so a percentage is never presented without the reasoning behind it. The methodology page documents each threshold, and the accuracy and limitations page sets out what the model cannot observe.
This site does not publish closure thresholds for any school system, because those are operational judgements rather than published numbers. What it can do is point you at the organisations that actually decide. Around Calgary, AB those include:
Treat the estimate on this page as a reason to prepare and to keep checking, never as an announcement. A school system can close buildings, delay the start, cancel transportation only, dismiss early or move to a different learning format, and those outcomes are not interchangeable.
Primary sources for weather warnings and road conditions covering Calgary. School decisions still come from the systems listed above.
Calgary questions
This page estimates weather pressure only, and in Calgary the realistic outcome is usually a transportation change rather than a closure. The Calgary Board of Education and the Calgary Catholic School District publish route and system status on their own transportation pages.
A chinook is a warm, dry downslope wind off the Rockies that can raise temperatures sharply within hours. The school-relevant problem is what follows: meltwater refreezes when temperatures drop back, leaving ice on residential streets, walkways and bus stops.
Divisions more commonly cancel or modify transportation during extreme cold than close schools outright. Each division sets its own approach, so this site publishes no threshold temperature. Check the division's transportation page during a cold warning.
On the transportation pages of the Calgary Board of Education and the Calgary Catholic School District, which publish route and system status early in the morning during cold snaps and after snowfall. This calculator estimates weather pressure and has no access to those service feeds.
Both are scored and both are visible in the result. In Calgary the temperature and wind chill factors frequently carry the number while snow and ice stay low, and the factor breakdown shows exactly which inputs produced it.
Still deciding what to do with the number? Read how schools make the final call and the guide to the best times to check a forecast.