Snow Day Calculator FAQ
What should you know about the Snowday snow day calculator? It is free, instant, and no sign-up; it is US-only; it scores full closures (not delays) from 48 hours of Open-Meteo forecast data; and the best time to check is between 6 p.m. and 10 p.m. the night before. All eight questions and answers are below.
Is the Snowday calculator free?
Yes — 100% free, instant, and no sign-up. There are no accounts, paywalls, or ads inside the results. The tool runs in your browser and pulls free public weather data from Open-Meteo, so there is nothing to install and nothing to subscribe to.
How accurate is a snow day calculator?
It's a smart guess, not a guarantee. The score reliably separates big-storm mornings from quiet ones, but real closure decisions are made by humans around 4 a.m. weighing roads, buses, and ice. Treat anything above 60% as a good reason to keep your boots by the door.
What weather data powers Snowday?
Open-Meteo, a free public weather API that blends government forecast models, including NOAA and ECMWF inputs. We request the next 48 hours of hourly snowfall, snow depth, temperature, wind, and precipitation probability for your exact location. Open-Meteo data is published under the CC BY 4.0 license.
Does the snow day calculator work outside the US?
Not yet — it currently covers US ZIP codes and cities only. Snow day customs differ enormously by country, so the scoring formula is tuned to how American districts decide. Enter a US location, or try a major city like 'Buffalo, NY' to see it work.
When is the best time to check for a snow day?
Between 6 p.m. and 10 p.m. the night before. By then the evening model runs have usually locked in overnight snow totals and the score settles. Districts make the final call between about 4 a.m. and 6 a.m. the next morning, so overnight changes are possible.
What raises a snow day chance the most?
Snow falling during the 5–9 a.m. commute window, which our formula weights 1.5× heavier than overnight snow — roads are unplowed and buses roll at exactly that time. Very cold air below 15 °F and winds of 20 mph or more add blowing and drifting risk on top.
Can the tool predict two-hour delays?
No — it scores full-day closures only. A 2-inch dusting at 5 a.m. often means a delayed start rather than a closure, and our score will correctly stay low for it. Watch your district’s official channels for delay announcements; most post decisions by about 6 a.m.
Why did my school close when the score was low?
Real superintendents weigh things we cannot see: bus driver shortages, ice on untreated side roads, downed power lines, or a storm that shifted 30 miles overnight. Rural districts also close on less snow than city districts. Treat the score as one input, not the decision.
Still curious?
The bottom line: the methodology page documents every formula weight, and the state guides explain closure norms where you live.
If your question is not answered here, send us a note — we read everything and add real questions to this page.