How accurate is the snow day calculator?
We test every version against what schools actually did. Run on the last three winters in 54 districts, on nights the engine gave 80% or higher, school closed 89% of the time, and on days it gave 0%, school was open on 9,987 of 9,989. It missed some too: 131 of 324 snow days had a chance under 50% the night before. Those are tests on past winters, not live predictions. Chances two or three days out are rougher, because the forecast itself is. The hardest cases are temperatures near freezing, where a degree decides between rain and ice. Every number is on our accuracy page.
When should I check for the most accurate prediction?
After 6 PM the evening before. Forecasts get more reliable as the morning gets closer, and by the evening before, the forecast for the next morning is usually settled. Districts that wait for the morning usually make the call between about 4:30 and 6:30 AM, after checking the roads. Checking the night before gives you the best available read before the decision is made.
Does this tell me whether my school is actually closed?
No. This is an independent prediction based on the weather forecast, not an announcement feed. We have no access to any district's internal decision. Always confirm an actual closure with your school or district directly: their website, phone line or official social accounts.
Why is the two-hour delay probability different from the closure probability?
They answer different questions. A delay is the tool districts use when conditions are bad early but expected to improve, such as a storm that ends by 6 AM or roads that need two more hours of plowing. A closure is for conditions that will not improve in time, or that arrive later in the day. A storm ending at dawn can have a high delay probability and a low closure probability at the same time.
Why does the same amount of snow give different results in different places?
Because districts have genuinely different thresholds. Two inches closes schools across much of the South, where there is little plowing equipment and drivers have less winter experience. The same two inches barely registers in Minnesota or Manitoba. The chance reflects how schools near you actually handle winter, not a national average.
Why do rural districts close more often than nearby city districts?
Bus routes. Rural districts cover long distances on roads that are plowed late or not at all, and pick students up in the dark on shoulderless country roads. A city district on the same forecast has shorter routes on treated main roads. It is common for a rural district to close on a forecast that leaves a neighboring urban district fully open.
Do colleges and universities get snow days?
Rarely, and they behave differently from K-12 schools. Most students live on or near campus so buses are not a factor, and closures generally require severe conditions rather than routine snow. Colleges also tend not to issue two-hour delays, opting instead to cancel specific class blocks or move online.
Is the calculator free?
Yes, entirely free. There is no account, no sign-up, and we do not collect personal information. Enter a location and school type and you get the prediction.
Want the details? The accuracy page has every test result, and the methodology covers definitions, data and known limitations.
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