How to use the snow day calculator
- Type your ZIP code (or a town name) and press Check. You can also tap Use my location.
- Pick how your area handles snow. A school in Atlanta closes for an inch; a school in Buffalo may stay open with eight.
- Add how many snow days your district has already used this winter, if you know.
- Read your chance of a snow day and a 2-hour delay. The table shows the next three mornings so you can see which day looks most likely.
No forecast handy, or want to test a what-if? Switch to Enter it myself and type the snowfall, temperature, wind and ice you expect.
How we estimate the chance of a snow day
Superintendents usually make the call between 4 and 6 a.m., mostly based on whether buses and student drivers can travel safely. The calculator copies that decision. For each school morning it reads the hourly forecast and looks at:
- Overnight snow from 6 p.m. the evening before to 7 a.m. This matters most, because roads have no time to be cleared.
- Daytime snow from 7 a.m. to 3 p.m., counted at half weight. Heavy daytime snow causes early dismissals and some closures.
- Freezing rain and sleet. A thin glaze of ice closes more schools than several inches of snow, so ice hours count heavily.
- Extreme cold. Wind chills far below zero close schools even without snow, because students wait outside for buses.
- Strong winds, which cause drifting and whiteouts when snow is falling.
Those factors become a single “storm score” in inches of snow, which is then scaled by how well your area handles snow and turned into a percentage with a smooth curve:
In an area with “some snow most winters”, a 2-inch overnight snowfall gives about a 12% chance, 4 inches about 49%, and 6 inches about 86%. The 2-hour delay chance uses the same score with a lower threshold, since districts delay for lighter snow than they close for.
How much snow closes schools?
There is no national rule. Each district decides, and what closes school depends mostly on how often a place sees snow and how many plows it owns. These are typical overnight snowfall amounts that close schools:
| Type of area | Examples | Snow that often closes school |
|---|---|---|
| Rarely gets snow | Atlanta, Dallas, Nashville, Raleigh | 1–2 inches, or any ice |
| Some snow most winters | Philadelphia, Washington D.C., Kansas City | 3–6 inches |
| Lots of snow | Buffalo, Minneapolis, Denver suburbs | 8 inches or more, or dangerous cold |
Rural districts with long bus routes and hilly roads tend to close sooner than city districts where many students walk.
Worked example
A school in an area with some snow most winters. The forecast shows 5 inches overnight, 1 inch in the morning, a low of 22°F and light winds.
Storm score = 5 + 0.5 × 1 = 5.5. That works out to about a 79% chance of a snow day, and a delay is very likely if school does open.
The same storm in an area that rarely sees snow scores 5.5 × 2.4 = 13.2, about a 99% chance. In the snow belt it scores 3.0, about a 27% chance.
How to tell if tomorrow will be a snow day
- Check the timing. Snow that starts after midnight and peaks around the morning commute is the most likely to close schools.
- Watch for ice. A winter storm warning that mentions freezing rain is a stronger signal than a big snow total.
- Check again late in the evening. Forecasts change. Run the calculator again after the 10 p.m. news, when the storm is closer.
- Sign up for district alerts. Most districts text and email families and post on their website by 6 a.m.
- Count the spare days. Districts that have used their built-in snow days may switch to remote learning or delays instead.
Planning around the school calendar? The days between dates calculator counts the school days left until a break.
Frequently asked questions
How accurate is the snow day calculator?
It is as good as the forecast and the area setting. When a storm is well forecast, it gives a realistic chance. It cannot know your superintendent's habits, road crews or a district's remote-learning policy, so treat it as an estimate and check your district's official announcement.
Where does the weather forecast come from?
Hourly forecasts come from Open-Meteo, a free service that combines national weather models such as NOAA's GFS and HRRR. Your ZIP code or town is sent to look up the coordinates and forecast, and nothing else about you is collected.
Does freezing rain close schools more than snow?
Usually, yes. A small amount of ice makes roads and sidewalks dangerous and is harder for plows to clear, so many districts close for an ice storm that leaves less than an inch of snow.
Can it be a snow day without any snow?
Yes. Extreme cold, with wind chills around −20°F or lower, closes schools in many northern districts because students wait outside for buses. Widespread power outages and flooding from melting snow can close schools too.
What is the difference between a snow day and a 2-hour delay?
A delay gives road crews a few more hours of daylight to clear and treat roads, so schools open late but still hold classes. Districts delay for lighter snow or for ice that should melt by mid-morning, and close when roads will still be unsafe.
When do schools announce snow days?
Most districts decide between 4:30 and 6 a.m. and announce by text, email, social media and local TV. Some announce the evening before when a major storm is certain.