See how a location search becomes a simple snow-day percentage, which weather factors influence the score, and why the result should be treated as a prediction rather than an official school closure notice.
The calculator uses forecast information for your selected location, focuses on tomorrow's local forecast, and converts several winter-weather signals into a 0–100 prediction score.
These signals include snowfall, temperature, wind, ice and visibility. You can read a more detailed explanation of each signal in our Weather Factors guide .
The process is designed to be quick for visitors while still being transparent about what happens behind the result.
A 5-digit ZIP code uses the United States ZIP forecast route. A city name can be geocoded to latitude and longitude for worldwide searches.
The site requests forecast data from OpenWeatherMap. The current implementation uses the 5-day / 3-hour forecast feed.
Forecast intervals that fall on tomorrow's local date are selected. If tomorrow cannot be isolated, the nearest forecast period is used as a fallback.
The calculation totals snow, tracks the lowest temperature and strongest wind, looks for freezing precipitation, and checks the lowest visibility.
Snow creates the main starting score. Colder temperatures, stronger winds, ice risk and poor visibility can increase it, while warmer temperatures can reduce it.
The final value is limited to the 0–100 range and translated into a simple label such as Low chance, Possible, High chance or Very high chance.
The result answers a practical question: how favorable do tomorrow's forecast conditions look for a snow-related school disruption? It is not a statistical guarantee that a school will close.
Real decisions may depend on factors the public forecast cannot fully capture, including road treatment, bus routes, local terrain, staffing, building access, local policy, power outages and whether a district uses remote learning.
If you want a broader overview of snow-day topics, visit our Snow Day Guides .
Forecasts update as a storm approaches. A change in snowfall timing, temperature, wind or freezing precipitation can move the score up or down.
For that reason, the most useful pattern is to check once when a storm becomes likely, again the evening before school, and once more early in the morning if the decision is still uncertain.
You can return to the Snow Day Calculator whenever updated forecast data becomes available.
18% — only weak winter-weather signals are present.
47% — conditions are becoming uncertain; a delay or local closure may be possible.
74% — several forecast factors look favorable for meaningful disruption.
91% — severe or disruptive winter conditions may be present, but only the school can confirm closure.
Check your current snow-day percentage →The calculator needs consistent forecast information so the same basic scoring approach can be applied across supported locations.
City searches can be converted into coordinates, allowing the calculator to support locations beyond US ZIP codes.
Three-hour forecast intervals make it possible to examine temperature, wind, precipitation and visibility across the day rather than using only one daily value.
Using one structured weather source allows the site to apply the same scoring rules consistently across supported locations.
Understanding the calculator is only one part of understanding a snow-day prediction. Conditions such as snowfall amount, freezing rain, temperature, visibility and wind can influence how disruptive a winter storm becomes. Read our Weather Factors guide for a closer look at these forecast signals.
Our Snow Day Guides provide additional information about snow-day probability, school closures, forecast interpretation and when to check your prediction.
If you want quick answers about accuracy, snowfall thresholds, ice, school closures or when to check your score, visit the Snow Day Calculator FAQ .
Enter your location and get a quick weather-based snow-day estimate.