Cold day calculator
Your school
Next school day
Cold day–%
Late start–%
Enter a ZIP code above
Will there be a snow day?
- An estimate from the public forecast. Your school district makes the call.
Why the sign says so
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Snow
How many inches are forecast, against what your area usually handles.
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Timing
Whether it falls overnight or stops early enough for plows to finish.
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Ice
Freezing rain, which closes schools at far smaller amounts than snow.
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Cold
The wind chill while children wait for the bus.
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Wind
Gusts strong enough to drift snow back over cleared roads.
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Alerts
Winter warnings and advisories from the National Weather Service.
Set from your state when you check a ZIP code. Change it if you know your district better.
Worked out in your browser from the National Weather Service forecast. No account, no cookies.
The chance school is closed or delayed for cold, from the wind chill forecast for your ZIP code.
How cold closes school
The calculator reads the lowest wind chill between 5 and 9 a.m., when children wait for buses. Cold starts to count 20 degrees above your district's line and reaches even odds at the line. Snow, ice and wind in the same forecast are added on top, so the sign shows the whole picture and the Cold row under it shows what the cold contributes.
| Wind chill | Closes for a dusting | Closes for a few inches | Used to snow | Almost never closes |
|---|---|---|---|---|
| 0°F | 27% | 5% | 0% | 0% |
| -10°F | 73% | 27% | 5% | 0% |
| -20°F | 88% | 73% | 27% | 5% |
| -30°F | 88% | 88% | 73% | 27% |
| -40°F | 88% | 88% | 88% | 73% |
These lines are our judgement, not district policy. Some districts publish their own threshold; where yours does, it is the number that counts. The full method is on the How it works page.
Questions about cold days
How cold does the weather have to be for school to be closed?
There is no national rule. The calculator treats a morning wind chill of about -25°F as a coin flip for districts used to winter and about -5°F for districts that are not. Each district sets its own practice.
What is a cold day?
A day when school is closed or starts late because of dangerous cold rather than snow. The risk is frostbite for children walking or waiting for a bus, and buses that will not start.
Is it the temperature or the wind chill that counts?
Wind chill. It describes how fast exposed skin loses heat, which is what matters at a bus stop. The calculator uses the lowest wind chill forecast between 5 and 9 a.m.
Is a delay or a closure more likely in extreme cold?
A delay, when the cold is worst at dawn and eases by mid-morning. A closure, when the wind chill stays dangerous all day.