Snow Day Calculator
Predict School Closure Probability with Evidence-Based Forecasting
Forecast Parameters
Closure Probability
Snow Day Calculator — Will Your School Close?
Short answer: This Snow Day Calculator gives a transparent, evidence-based probability that a U.S. school district will cancel or delay classes. It combines forecasted snowfall (inches), precipitation chance (PoP), timing relative to school start, temperature, wind hazards, and your district's typical threshold and preparedness. Use it to plan and compare scenarios — not as the official announcement.
What drives a snow-day decision?
Decisions are typically grounded in road safety for buses, timing of the storm (morning impact is greatest), total accumulation and snowfall rate, and staffing/operational readiness. Local authorities consult road commissions, DOT crews, and transportation directors; they may also weigh staffing shortages (bus drivers or custodial staff), extreme wind-chill hazards, or infrastructure vulnerabilities. Because coverage and thresholds differ by region, we let you set your district's threshold and preparedness so the calculator adapts to local practice.
How this tool models probability
The calculator uses an explainable weighted model, not a black-box prediction. The largest contributor is snowfall relative to a district threshold — if predicted snowfall meets or exceeds your district's policy threshold, probability rises quickly. Precipitation probability (PoP) scales confidence in the forecast. Storm timing applies a multiplier (morning storms matter most). Temperature and high winds add hazard scores because they increase road icing and reduce visibility. Finally, district preparedness (plows, salt, staffing) reduces the estimated chance of closure.
Why editable thresholds matter
U.S. districts have different operational practices. For example, a rural district with long bus routes might close for 2–3" while an urban district that's heavily plowed might remain open for 6–8". Using editable thresholds lets parents and staff mirror local rules precisely and run "what-if" scenarios quickly: change the snowfall from 2.5" to 4" and watch how the chance changes.
How to use the calculator (best practice)
- Use the latest forecast values from the National Weather Service or a trusted local meteorologist.
- Set your district threshold to published guidance if available (district websites often publish closure policies).
- Test timing scenarios — overnight vs morning arrival can swing the probability.
- Re-run predictions after model updates (forecasts often change 24–48 hours before an event).
Interpreting results & limitations
The percent result expresses the estimated probability given the inputs. It is not a definitive closure decision. Districts sometimes consider real-time road reports, bus diagnostics, and mutual aid (neighboring road crews). Use this tool for early planning; expect official announcements from your district early morning if a closure is likely.
Frequently Asked Questions
A: No. This is an evidence-based probability estimate. Official decisions come from your local school district.
A: It models key drivers. Use the threshold and preparedness sliders to reflect your district's practice.
A: We recommend updating your inputs as new forecasts become available, especially 12-24 hours before the storm.
A: Storms arriving during morning commute hours create immediate safety concerns, while overnight storms give crews more time to clear roads.