Will tomorrow be a snow day?
Snow Day Calculator. Enter your ZIP code to estimate the chance of a snow day tomorrow, based on the National Weather Service forecast for tonight and tomorrow.
Example Not a real forecast: enter your ZIP above.
chance
e.g. 5 in of snow overnight, low of 24 °F
3-day snow day outlook
Each day uses the same formula on that night and the following daytime forecast period. Days further out are less certain, and weekend days are shown even though there is no school.
How the snow day chance is calculated
We read the National Weather Service gridded forecast for your exact location and add up what is expected from the start of tonight through the end of tomorrow's daytime period. Then we apply a simple, published formula:
- Snowfall points. Under 0.5 in: 0. From 0.5 to 2 in: 10–25 points. From 2 to 6 in: 25–75 points. Above 6 in: 75 points plus 4 per extra inch, capped at 85.
- Warm ground penalty. If the lowest temperature in the window stays above 34 °F, snowfall points are halved, because snow tends to melt on roads.
- Ice points. Any ice accumulation: 10. At least 0.1 in: 25. At least 0.25 in: 45.
- Confidence. Snow and ice points are multiplied by 0.5 + 0.5 × (highest precipitation probability ÷ 100).
- Extreme cold points. Wind chill of -15 °F or lower adds 15; -25 °F or lower adds 35.
The 3-day outlook repeats the same calculation for each of the next three night-plus-day windows in the National Weather Service forecast. The headline number is always tomorrow.
The result is capped at 95%, because no forecast can guarantee a closure. With clear, mild weather every term is zero, so the chance is 0%.
What schools actually look at
Superintendents usually decide early in the morning, after checking road conditions with transportation staff and neighboring districts. Timing matters: snow that ends by midnight may be cleared in time, while snow starting around 5 AM hits the bus routes directly. Districts in the South may close for an inch of snow, while districts in snowy regions often stay open with several inches. Treat this number as a guide and always follow your school's official announcement.
When do schools announce snow days?
There is no national rule. Many districts make the call early in the morning of the school day, after transportation staff have driven the bus routes, so that families hear before buses leave. When a major storm is clearly forecast, some districts announce the evening before. Decisions are usually posted on the district website and social media, sent by text, email or phone alert, and passed to local TV and radio stations. Check your own district's page to see which channels it uses.
What drives the decision
- Snow amount. More snow means more roads to clear, but the threshold depends heavily on the region and on how many plows and salt trucks the town has.
- Ice. Freezing rain and sleet are often more disruptive than snow, because a thin glaze can make roads, parking lots and sidewalks unsafe.
- Timing. Snow that ends overnight may be cleared by morning. Snow or ice arriving during the early-morning bus runs or the afternoon dismissal is harder to manage.
- Wind chill. Students wait at bus stops and walk to school, so dangerously cold wind chills can lead to closures or delays even without snow. The National Weather Service issues cold weather advisories and warnings for these conditions.
- District differences. Rural districts with long bus routes and unpaved or hilly roads may close when nearby city districts stay open. Districts also differ in how many make-up days they have built into the calendar and whether they can switch to a remote learning day.
Delays and early dismissals
A closure is not the only option. Many districts use a delayed opening, often two hours, to give road crews time after overnight snow, or dismiss early when a storm is expected to arrive during the day. This calculator estimates conditions for the whole night-and-day window, so a middle score can mean a delay is more likely than a full closure.
Free snow day widget for your site
News stations, weather blogs and school pages can embed the calculator for free. It uses the same National Weather Service forecast and links back to this page.
<iframe src="https://snowdayradar.online/embed/?zip=04101" width="320" height="220" title="Snow day chance" loading="lazy" style="border:0"></iframe>Replace the ZIP with your area.
Frequently asked questions
How accurate is this snow day calculator?
It is an estimate, not a prediction of what your school district will decide. It uses the official National Weather Service forecast for your area, but closures also depend on road crews, district policy, bus routes and how many snow days have already been used.
Where does the weather data come from?
Your ZIP code is converted to a latitude and longitude with the free Zippopotam.us service, and the forecast comes directly from the National Weather Service (api.weather.gov). Nothing is stored on our side.
Why does it show 0% when it is cold?
Cold alone rarely closes schools. The score only rises from cold when the forecast wind chill reaches -15 °F or lower, which is the range where many northern districts start considering closures or delays.
What time window is used?
The calculator looks at tonight and the next daytime forecast period, because snow overnight and during the morning commute matters most for school decisions.
Does it work outside the United States?
No. The National Weather Service only covers the US and its territories, and the ZIP lookup only accepts 5-digit US ZIP codes.
Why is ice weighted so heavily?
Even a tenth of an inch of freezing rain makes roads and sidewalks dangerous for buses and students, so districts often close for ice amounts that would be minor as snow.
How does a snow day calculator work?
It turns a weather forecast into a single estimate. This one reads the National Weather Service forecast for your ZIP code, adds up snow and ice from tonight through tomorrow, checks temperature and wind chill, and applies the published formula on this page.
What time do schools announce snow days?
It depends on the district. Many decide early in the morning after checking the roads, and some announce the night before when a big storm is certain. Your district website and its text or email alerts are the official source.
How many inches of snow does it take to cancel school?
There is no single number. A district that rarely sees snow may close for a light coating, while districts in snowy regions often stay open with several inches if roads are plowed in time. Ice and the timing of the snow often matter as much as the total.
Can school be cancelled for cold weather without snow?
Yes. Some districts close or delay school when wind chills are dangerously low because students wait outside for buses. This calculator adds points when the forecast wind chill reaches -15 °F or lower.
Does it predict delayed openings?
Not separately. A middle score usually means conditions are borderline, which is when districts are more likely to use a delay instead of a full closure.
Can I see the chance for the next few days?
Yes. After you enter a ZIP code, the 3-day outlook shows an estimate for each of the next three night-and-day windows. Forecasts further out are less reliable, so check again closer to the day.
Will there be a snow day tomorrow?
Enter your ZIP code above. The calculator reads the National Weather Service forecast for tonight and tomorrow and turns snow, ice, temperature and wind chill into an estimate. Only your school district can announce a snow day, so check its website or alerts too.
Will there be a snow day on Monday?
If Monday is within the next three forecast windows, the 3-day outlook under the main result shows an estimate for it. On a Friday or Saturday, check again on Sunday evening, when the forecast for Sunday night and Monday is more reliable.
Does the snow day calculator work in Michigan and other snowy states?
Yes. It works for any 5-digit US ZIP code, including Michigan, Minnesota, New York and the rest of the snow belt. Districts in snowy states usually need more snow to close, so treat a middle score there as borderline.
Can it predict snow days for college?
It estimates the weather risk, not a decision. Colleges often stay open or switch to remote classes in conditions that close K-12 schools, so check your college's alerts.