Free snow day estimator for U.S. schools
Snow Day Calculator: will school be closed or delayed?
Enter a U.S. ZIP code to check the next two school mornings against the National Weather Service forecast, or type in the snow, timing, cold and ice yourself. The calculator weighs snow that falls just before the buses run more than snow that stopped earlier, adds ice and dangerous wind chill, and adjusts for how used to snow your area is. It shows a band for a closure and a delay, and lists the reasons, so you can judge the result yourself.
Checking sends this ZIP code’s approximate coordinates to the National Weather Service for its forecast. The ZIP code itself is not sent, and nothing is stored.
Example outlook
Example only: 4 in of snow overnight, a low of 22 °F and a 10 mph wind, in an area that sometimes gets snow. Check your ZIP code for a real forecast.
Closure risk is moderate and delay risk is high.
Why
- Snow: about 4 in in total (4 in before 6 am), which the model weights by timing to 3.4 in for a closure and 2.8 in for a delay. For an area that sometimes gets snow, a closure reaches the midpoint of the scale at about 6 weighted inches and a delay at about 3.
- Cold: a wind chill near 11 °F is cold but below the level the model treats as a reason to close.
This is a rough estimate from a simple rule-of-thumb model, not a prediction and not a school decision. The scores are not probabilities and have not been tested against real closures. Districts set their own rules, so confirm with your district.
Checking a ZIP code converts it to approximate coordinates in your browser, using a table on this site, and sends those rounded coordinates to the National Weather Service for its forecast. Nothing you enter is stored, and there is no account. This is an independent estimate from a simple model, not a prediction and not an official decision. It is not affiliated with any school or district. Confirm closures and delays with your district.
How to use the snow day calculator
Choose Forecast for my ZIP code, type a five-digit ZIP code and select Check forecast. The calculator loads the National Weather Service forecast for that area and lets you pick the next two school mornings. If you prefer, choose Enter the forecast myself and type the expected snowfall, when it falls, the overnight low, the wind and whether ice is expected.
Set how used to snow your area is. It starts from your state, which is only a rough guide: a northern town and a southern town in the same state often deal with snow very differently.
What the result means
You get two bands, one for a full closure and one for a delay, from very low to very high, each with a score out of 100 and a list of reasons. The scores are not probabilities. They show how a simple, openly described model weighs the forecast. If nothing is in the forecast, the calculator says so and the closure band is very low.
A delay is only an option if your district uses delays. A high closure band may mean a remote learning day if your district holds those.
What it cannot know
It cannot see your district’s rules, equipment or plans, the exact conditions on your roads or a decision that has not been made. Forecasts change, and a ZIP code’s center point can be miles from your street. Use the estimate to decide how closely to watch your district’s announcement, and follow the district’s decision.
How the estimate is built
The model is deliberately simple and fully described here. It sorts forecast snow into four time windows, weights each one, and compares the total with a midpoint for your area. Then it adds ice and cold.
- Timing: snow in the three hours before 6 am counts fully for a closure. Earlier snow counts 70 percent, snow from 6 to 9 am 80 percent, and snow during the school day 35 percent.
- Snow tolerance: the midpoint of the closure scale is about 3 weighted inches for areas that rarely get snow, 6 for sometimes and 10 for often. For a delay it is half of that.
- Ice: 0.25 inch of ice or more counts as a serious hazard; smaller amounts or a freezing rain risk add less.
- Cold: wind chill adds points in three steps that depend on how snowy your area is, for example 15, 25 and 35 °F below zero for areas that often get snow.
- Result: the highest of the snow, ice and cold scores, plus 30 percent of the others, gives the closure score. A delay-only outcome is reduced when a closure is already likely.
Where the forecast comes from
The forecast is the National Weather Service gridpoint forecast, which includes hourly snowfall, ice accumulation, temperature, wind and wind chill. Your ZIP code is converted to a nearby point using a table built from the U.S. Census Bureau’s ZIP Code Tabulation Area internal points. Only the rounded coordinates go to the National Weather Service. The National Weather Service describes its API data as open and free to use for any purpose.
No accuracy claim, no school affiliation
We have not measured how often this model matches real decisions, so we do not give an accuracy rate. Its thresholds are our assumptions, not district rules. Snow Day Calculator is not affiliated with any school, district or government agency, and the result is never an official announcement.
More snow day tools
Delay or closure, and wind chill.
Two-Hour Delay Calculator: delay or closure?
Enter the expected snow, when it starts and ends, ice and the morning cold to see whether a two-hour delay or a full closure looks more likely, and why.
Wind Chill Calculator: the NWS formula, and cold school closures
Calculate wind chill from the air temperature and wind with the National Weather Service formula, in °F or °C, and see how cold alone affects the chance of a school closure.
The studio notebook
A useful place to begin.
Clear steps, considered details, and ideas you can put to use.
How much snow closes schools? It depends where you live
There is no national number. Here is why the same snowfall closes schools in one place and not another, and how the calculator’s snow-tolerance setting reflects that.
How school districts decide on snow days, and when you hear
Who makes the call, how early it happens, how families are notified, and what a two-hour delay changes, using published policies from real districts.
Snow days vs remote learning days: what changes for families
Some states let districts hold school online instead of closing. How a remote day works, what limits apply, and how to read a closure announcement.
Extreme cold and wind chill: when cold alone closes schools
How wind chill is calculated, what the National Weather Service cold alerts mean, and why there is no single wind chill at which schools close.
How the Snow Day Calculator works, and what it cannot know
The forecast source, the scoring rules and their limits, written out so you can judge the result for yourself.
The night before a possible snow day: a parent’s checklist
What to check in the forecast, which alerts matter, and how to be ready for a delay, a closure or a remote day.
A few helpful answers
Before you begin.
How accurate is the snow day calculator?
We have not measured its accuracy and do not claim one. It is a simple model that weighs a public forecast. Districts make their own decisions, and forecasts change.
Where does the forecast come from?
From the National Weather Service gridpoint forecast for the point near the center of your ZIP code.
Is my ZIP code stored or sent anywhere?
Your browser converts the ZIP code to approximate coordinates using a table on this site. Only the rounded coordinates go to the National Weather Service, and nothing is stored by this site.
Can I use it without entering a ZIP code?
Yes. Choose Enter the forecast myself and type the expected snow, timing, cold and ice. That mode makes no forecast request.
Why does it say no snow in the forecast?
The National Weather Service forecast shows little or no snow, ice or dangerous cold for the morning you chose, so the closure band is very low. Outside winter that is the usual result.
Does it work outside the United States?
No. It uses U.S. ZIP codes and the National Weather Service. You can still use the manual mode anywhere.
Is this tied to my school district?
No. It is not affiliated with any school or district. Always confirm with your district’s official announcement.