About Snow Day Calculator

Our Story

Snow Day Calculator was built with a simple goal: give US families a modern, accurate, and completely free tool to predict whether school will be cancelled due to snow. We've all been there — lying awake the night before a big storm, anxiously checking weather apps that tell you how much snow is coming but not whether school will actually close.

The original snow day calculator was famously built by a middle-schooler in 2007 and grew to attract millions of visitors. We built our version with modern technology and a better algorithm, keeping the spirit alive for a new generation of students who want to know: will school be cancelled tomorrow?

How the Algorithm Works

Our prediction system uses a weighted scoring model based on four key factors, all calibrated against real-world school closure data:

• Snowfall (45%): Expected inches in the next 24 hours. The biggest single factor. Adjusted for regional differences — 2 inches in Texas is not the same as 2 inches in Minnesota.
• Temperature (30%): Minimum low temperature, including wind chill effects. Extreme cold can trigger closures even without snow.
• Wind Speed (15%): Maximum wind gusts. High winds combined with snow create blizzard conditions and dangerous visibility for school buses.
• District Baseline (10%): A base probability adjusted by the district's closure policy (liberal, neutral, or conservative).

The final probability is capped at 95% — no tool can guarantee a school closure, because the decision always rests with the school superintendent.

Our Data and Methodology

We utilize advanced numerical weather prediction datasets and geocoding services to retrieve real-time regional weather information. Our calculations are based on historical US school closure patterns and meteorological research, combining temperature, snowfall, and wind speed metrics to provide accurate, localized estimations.

Our Commitment

We are committed to three things: accuracy, privacy, and free access. We do not store ZIP codes or any personally identifiable information — all weather lookups happen in your browser in real time. We don't require registration or email addresses. The tool is, and always will be, free to use for everyone.

Weather prediction isn't perfect, and neither is ours. We encourage users to always verify school closures through official district channels, local TV stations, and emergency notification systems. Our tool is a helpful guide — not an official announcement.