A snow day percentage is best understood as a planning signal, not a measured guarantee. Its quality depends on the weather forecast, the model's assumptions and information that no public calculator can observe in real time.
What the estimate is actually measuring
Our calculator converts forecast snowfall, possible icing, temperature, wind and morning timing into a consistent score. It then adjusts for broad school and area settings. The full weighting method is public, so a user can see why a result rose or fell.
The number does not represent a district's own forecast, and it is not trained on a complete history of every school system. We deliberately avoid unsupported claims such as a universal “95% accuracy” rate. Without a published, independently auditable dataset, that kind of headline is not meaningful.
Why forecasts change
Weather models are rerun as new observations arrive. A small shift in storm track can move a narrow snow band, change precipitation type or alter the timing of the heaviest period. Open-Meteo combines output from multiple national weather services into regularly updated time series, but each variable still contains uncertainty.
That is why a prediction made several days early should carry less decision weight than one made the evening before. Follow the best-time-to-check routine instead of treating the first number you see as fixed.
What the calculator cannot observe
- actual pavement temperature and untreated side roads;
- bus driver and substitute staffing;
- power, heat or water problems at a school building;
- district-specific attendance and remote-learning rules;
- the final judgment of local administrators.
Those limits are not defects to hide; they define the proper use of the tool. Learn more about the operational decision schools make and review our accuracy statement before relying on any result.
A responsible way to use the percentage
- Use an early estimate to decide whether to prepare childcare, travel or remote-learning plans.
- Recheck as the storm approaches and compare the factor breakdown—not only the final number.
- Read current weather alerts and official updates.
- Treat your district's announcement as the only authoritative closure decision.
Good uncertainty is useful. A transparent range of possibilities is more honest than a confident-looking number with no explanation.
