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Snow day calculator

Will school be cancelled tomorrow? Enter the forecast — temperature, snowfall, wind, snow already on the ground — plus your region, school type, road conditions and whether freezing rain is expected, and this heuristic calculator estimates the odds of a snow day.

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Enter Unit system, Temperature (°F or °C), Snowfall forecast (in or cm), Wind speed (mph or km/h), Snow already on ground (in or cm), School type, Region, Road conditions, Freezing rain expected? and the Snow day calculator works out Snow-day probability, Verdict straight away. For instance, with Unit system = Imperial (°F, in, mph), Temperature (°F or °C) = 28, Snowfall forecast (in or cm) = 6, Wind speed (mph or km/h) = 15, Snow already on ground (in or cm) = 2, School type = Public school, Region = US South, Road conditions = Clear / dry and Freezing rain expected? = No it returns Snow-day probability = 93.1% and Verdict = high.

How to use it

  1. Enter your values: Unit system, Temperature (°F or °C), Snowfall forecast (in or cm), Wind speed (mph or km/h), Snow already on ground (in or cm), School type, Region, Road conditions, Freezing rain expected?.
  2. Read the result instantly: Snow-day probability, Verdict.

Frequently asked questions

What does the Snow day calculator actually compute?

It takes Unit system, Temperature (°F or °C), Snowfall forecast (in or cm), Wind speed (mph or km/h), Snow already on ground (in or cm), School type, Region, Road conditions and Freezing rain expected? and derives Snow-day probability and Verdict from them. The calculation is live as you type, so the result updates on every change.

What information do I need to provide?

9 values: Unit system, Temperature (°F or °C), Snowfall forecast (in or cm), Wind speed (mph or km/h), Snow already on ground (in or cm), School type, Region, Road conditions and Freezing rain expected?. Nothing else is required — no account, no file upload.

Can you show a worked example?

With Unit system = Imperial (°F, in, mph), Temperature (°F or °C) = 28, Snowfall forecast (in or cm) = 6, Wind speed (mph or km/h) = 15, Snow already on ground (in or cm) = 2, School type = Public school, Region = US South, Road conditions = Clear / dry and Freezing rain expected? = No, the calculator returns Snow-day probability = 93.1% and Verdict = high. Those figures come from running this exact tool, so you can reproduce them by entering the same values.

What happens if I enter larger values?

It moves a lot. Using Unit system = Metric (°C, cm, km/h), Temperature (°F or °C) = 56, Snowfall forecast (in or cm) = 12, Wind speed (mph or km/h) = 30, Snow already on ground (in or cm) = 4, School type = Private school, Region = Mid-Atlantic, Road conditions = Wet and Freezing rain expected? = Yes instead, Snow-day probability goes from 93.1% to 77% — which is why it is worth testing a few scenarios rather than trusting a single figure.

Which “Unit system” option should I choose?

You can pick between « Imperial (°F, in, mph) » and « Metric (°C, cm, km/h) ». Each one changes what the calculator works out, so switch and compare — the default is « Imperial (°F, in, mph) ».

What does it give for smaller values?

Scaled down to Unit system = Imperial (°F, in, mph), Temperature (°F or °C) = 14, Snowfall forecast (in or cm) = 0, Wind speed (mph or km/h) = 0, Snow already on ground (in or cm) = 0, School type = Public school, Region = US South, Road conditions = Clear / dry and Freezing rain expected? = No, Snow-day probability comes out at 36%. The relationship is worth checking at both ends before you rely on a single result.

When would I actually use this?

Answering a scheduling question exactly: how many working days until a deadline, what date falls sixty days out, and what time that is for a colleague elsewhere.

What is the most common mistake?

Counting days by subtracting dates and forgetting whether the endpoints are included. Inclusive and exclusive counts differ by one, which is the difference between meeting a deadline and missing it.

How accurate is it, and what are the limits?

A fun heuristic, not an official forecast. Real closures depend on local officials — always check your school district.

What is the difference between the Snow day calculator and the Sick day believability calculator?

This one returns Snow-day probability; the Sick day believability calculator returns Believability. That is the whole difference — open the one whose figure you need.

Further reading

All guides →
How-toHow to Convert Time Zones: UTC Offsets, Day Rollover and DSTConverting between time zones is adding or subtracting the difference in UTC offsets, then handling any day rollover. Learn the method, a worked example, and the DST caveat.How-toWhat Day of the Week Was I Born? Find Out in SecondsFind the weekday of any birth date. Learn the quick calculator method and a short introduction to the Doomsday rule for working it out in your head.ExplainerHow Daylight Saving Time Works: Spring Forward, Fall BackDaylight saving time shifts clocks an hour in spring and back in autumn. Learn spring-forward and fall-back, why one day is 23 hours and another 25, and how US and EU dates differ.How-toHow Many Days Have I Been Alive? Count Days, Weeks and MonthsYour age in days is the whole number of days between your birth date and today. Learn how to count it by hand, convert it to weeks and months, and why leap years matter.How-toCountdown to New Year: How to Count the Days and Weeks LeftBuilding a countdown to a target date is just counting whole days from today to the target, then splitting that total into weeks. Learn the method with a worked example.ExplainerWhat Generation Am I? Birth-Year Cutoffs ExplainedBoomer, Gen X, Millennial, Gen Z or Alpha? Learn the commonly used birth-year ranges, why the boundaries are fuzzy, and how to place yourself if you were born near a cutoff.