Formula Used
The calculator uses a weighted risk model. It does not replace official school alerts. It estimates how strongly weather and district factors support a snow day decision.
Closure Chance = base score + snow score + ice score + temperature score + wind score + timing score + road score + district score + bus score + history score + rural road score - remote readiness score.
Accuracy Index = 45 + forecast reliability adjustment + decision distance adjustment + snowfall clarity adjustment.
Error Band becomes smaller when forecast reliability is high. It also becomes smaller when the closure chance is far from 50%.
How to Use This Calculator
Enter the forecast snowfall, ice amount, low temperature, and wind gust. Add local road and district details. Choose how prepared the district is for remote learning. Press the calculate button. The result appears above the form. Use CSV or PDF buttons to save the current calculation.
Example Data Table
| Scenario |
Snow |
Ice |
Timing |
Road Treatment |
Likely Result |
| Light event |
2 in |
0.00 in |
Afternoon |
Excellent |
Low closure chance |
| Moderate storm |
6 in |
0.10 in |
Overnight |
Standard |
Possible closure |
| Heavy storm |
11 in |
0.25 in |
Morning commute |
Limited |
High closure chance |
About Snow Day Accuracy
A snow day decision is rarely based on snowfall alone. School districts usually look at road safety, bus access, ice risk, timing, and local readiness. A forecast with six inches overnight may matter more than the same total after school hours. Ice can also change the result quickly. Even a small glaze can make bus routes unsafe.
Why Timing Matters
Timing often drives the final call. Snow during the morning commute raises risk. Overnight snow gives road crews limited time. Afternoon snow may lead to early dismissal instead of full closure. This calculator gives extra weight to morning and overnight events.
Accuracy and Confidence
The accuracy index shows how dependable the estimate may be. A strong forecast, clear road conditions, and a closure chance far from 50% improve confidence. A result near 50% means the decision is unstable. Small changes in snowfall, ice, or district policy may shift the outcome.
Local Conditions
Local details matter. Rural roads, steep hills, long bus routes, and limited road treatment increase the chance of closure. A cautious district may close sooner. A strict district may wait for stronger evidence. Remote learning readiness can reduce full closures because schools may switch to online work.
Best Use
Use this tool as a planning guide. Enter realistic forecast values. Update the inputs when a new weather alert appears. Compare the result with official district messages. The calculator helps organize the main factors, but it cannot see every local hazard. Final decisions should always come from the school district or local authority.
FAQs
What does snow day accuracy mean?
It means the estimated reliability of the closure prediction. The calculator compares weather strength, local risk, and forecast reliability to create an accuracy index.
Is this calculator official?
No. It is a planning tool. Always follow school district alerts, local emergency notices, and official weather updates.
Why does ice increase the score so much?
Ice can make roads unsafe with little accumulation. Buses, hills, sidewalks, and untreated roads become risky quickly during freezing rain.
Why does timing affect the result?
Snow during morning travel is harder to manage. Overnight snow also gives crews less time before buses start routes.
What is forecast reliability?
It is your trust level in the current forecast. Use a higher value when forecasts agree and alerts are consistent.
Can this predict delays?
It focuses on closure chance. A moderate result may still suggest a delay, especially when snow ends before morning travel.
Why include past closure rate?
Some districts close more quickly than others. Past behavior helps adjust the estimate for local decision patterns.
When should I recalculate?
Recalculate after each major forecast update. Also update it when ice, wind, or road treatment information changes.