Snow Day Calculator
Will there be a snow day tomorrow? Most snow day calculators run a forecast through the same rule of thumb for the whole country. We do something better: we weigh the forecast against what your own town has actually done on this date, across decades of NOAA records — because three inches closes schools in Atlanta and means nothing in Buffalo.
Enter a US ZIP code. We combine tomorrow's National Weather Service forecast with decades of snowfall records for your own town.
How the odds are worked out
We find the weather station nearest your ZIP code with a complete snowfall record — usually an airport, which reports every day rather than most days — and ask how often a single day around this date has produced enough snow to disrupt school.
"Enough" is set locally. A station that sees an inch of snow twice a winter gets a low threshold; one that sees it thirty times gets a high one. That historical rate is the starting point.
Then we bring in the National Weather Service forecast for your grid square. Tomorrow, the forecast does most of the work. Five days out it does about a third. Past a week there is no forecast worth having, and the answer settles back to what the records say.
Frequently asked questions
How does this snow day calculator work?
Two ingredients. First, the current National Weather Service forecast for your location — how much snow is actually expected tomorrow. Second, decades of snowfall records from the weather station nearest you, which tell us how often a day like this has historically produced disruptive snow where you live. The forecast carries most of the weight for tomorrow and progressively less further out, until beyond about a week it is the historical record alone.
How much snow does it take to close school?
It depends enormously on where you are, which is why we do not use one national number. Three inches shuts down much of Georgia and does not slow Syracuse down at all. We set the threshold from your own station: places that rarely see snow get a low bar, places that see it constantly get a high one. The calculator shows you the threshold it used.
Is this a guarantee that school will be closed?
No. We can tell you how much snow is forecast and how often that much snow has historically fallen on this date where you live. We cannot tell you what your superintendent will decide at 5am. Closure calls also turn on ice, timing, and road conditions, and daily weather records do not capture any of those.
Why are my odds so low even in winter?
Because these are the odds for one specific day, and a heavy snow on one particular date is genuinely uncommon almost everywhere. Even Buffalo in mid-January only produces a disruptive snowfall on about 7% of days. When a storm is actually in the forecast the number climbs sharply — that is the calculator working, not failing.
Where does the data come from?
Forecasts come from the National Weather Service. History comes from the NOAA Global Historical Climatology Network, the same daily station observations behind the rest of this site. We score the most recent 30 years rather than the entire record, because most stations have a century of data from a measurably colder climate and including it overstates the odds.