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Snow Day Calculator
Will school be closed tomorrow? Enter the forecast snowfall, when it is due, whether ice or bitter cold is involved and how much snow usually closes your district, and get an honest rule-of-thumb chance of a snow day, with every point of the estimate shown. It does not fetch weather data or any school’s decision.
A rule of thumb, not a forecast. Only your district can call it.
- In plain words
- Very likely by this rule of thumb
- Forecast as a share of your district’s usual closing amount
- 150%
How the estimate adds up
| Factor | Points |
|---|
Saved setups
Save a set of inputs you reuse — your usual rate, your loan, your room sizes — and load it back in one tap.
Your recent calculations
Results you calculate here are kept on this device so you can come back to them.
Formula
How to use it
- Enter the snowfall forecast for the night and early morning.
- Enter how much snow usually closes your schools; past closings are the best guide.
- Choose when it falls, what is falling and the wind chill expected at bus time.
- Read the chance, and the table that shows how it adds up.
Worked examples
6 in overnight where schools usually close at 4 in: 77 points for 150% of the threshold, × 1.15 for overnight timing
- Chance of a snow day
- 89%
- Forecast as a share of your district’s usual closing amount
- 150%
- In plain words
- Very likely by this rule of thumb
3 in of mixed snow and sleet during the commute, threshold 6 in, two snow days used: 12 × 1.25 = 15, + 15 for sleet, − 4
- Chance of a snow day
- 26%
- Forecast as a share of your district’s usual closing amount
- 50%
1 in of snow ending the evening before, then freezing rain, where 2 in closes schools: 12 × 0.75 = 9, + 35 for ice
- Chance of a snow day
- 44%
- In plain words
- Possible — a delayed start is more likely than a full closure
No snow, but a wind chill below −25 °F and three snow days used: 45 − 6
- Chance of a snow day
- 39%
- Forecast as a share of your district’s usual closing amount
- 0%
What actually drives a closing
The decision is usually made very early in the morning, often after staff have driven the bus routes. What matters most is whether roads, sidewalks and bus stops will be safe at pickup time, so snow that stops by midnight and gets plowed counts for far less than snow falling at 6 a.m. Ice is worse than snow: even a light glaze of freezing rain can close schools that would stay open for several inches of powder.
Local experience sets the threshold. Districts where snow is rare have few plows and untreated hills, so an inch or two can close them; snow-belt districts plan for routine storms and may stay open with 6 inches or more.
Read it as a rule of thumb
The points are a simple, transparent heuristic built from those patterns. They are not a model fitted to school-closure records and do not use live forecasts. Snowfall forecasts are given as ranges for good reason, so try both ends of the range. Your district’s website, alerts and local news are the only real answer.
Delays versus closures
When the call is borderline, many districts choose a two-hour delay, which gives road crews daylight to work. That is why results from 25% to 49% are labeled as a likely delay rather than a closure. Districts that have used up the snow days built into their calendar tend to lean toward delays or remote-learning days.
Questions people ask
How much snow does it take to close school?
It depends on where you live. As a rough guide, 1–2 in can close schools where snow is rare, 4–6 in in many northern districts, and 8 in or more in snow belts. Ice and timing often matter more than the total.
What are the chances of a snow day with 6 inches of snow?
If your district usually closes at 4 in and the snow falls overnight, this rule of thumb gives about 89%. If it usually takes 8 in, 6 in is 75% of the threshold: 30 points × 1.15 = about 35%.
Can cold alone close schools?
Yes. Some northern districts close or delay for extreme wind chill at bus time even without snow, because frostbite can set in on exposed skin within about 30 minutes at a wind chill of −25 °F, and faster as it gets colder.
Is this a snow day predictor?
It is an estimate from the inputs you give it, not a forecast or a prediction service. Only your school district decides, and it announces the decision itself.