The scorecard
How good is it?
We test Snow Day Radar the hard way: hide a whole winter, forecast it blind, then check every school morning against what districts really did. Here is the scorecard, misses included.
When it says 60%, do schools close about 60% of the time?
Every morning with winter weather in 15 Kentucky winters (19,888 mornings), grouped by the odds the site would have shown.
| Said | Schools closed | Mornings |
|---|---|---|
| Under 20% | 6% | 7537 |
| 20% | 25% | 1795 |
| 30% | 37% | 1219 |
| 40% | 45% | 976 |
| 50% | 57% | 817 |
| 60% | 64% | 827 |
| 70% | 71% | 882 |
| 80% | 89% | 5835 |
Better than counting inches
Compared with a plain “this many inches closes school” rule, its errors are 48% smaller, because it knows what 2 inches means in your district: how rare that snow is there, how hilly the bus routes are, and whether ice or cold is the real problem.
Two and three days out
Fed only the forecast as it stood each evening, it put closed mornings above open ones 95% of the time for the next school day, 93% two days out and 91% three days out. That is why outlooks use bigger steps.
What it still misses
- Light freezing drizzle that weather stations barely record.
- Districts that close the day before a big storm arrives.
- Sleet storms, which snowfall maps undercount. A fix is in testing.
- South Carolina passed its own test: 18,111 school mornings over 4 winters (2021-22 to 2024-25), each forecast the evening before and checked against the state's missed-day reports. When it said 80%, 89% of those mornings had no in-person school.
- Everywhere else the model is in beta: it ranks Arkansas closures well (96%) but runs low there, misses Texas ice-storm aftermath, and runs high in snowy northern states like Wisconsin, where a fix is in testing. Each state goes live only after its own test passes.
Source: the Snow Day Radar engine's backtests (11/7/2026). Closure records: Kentucky Department of Education amended school calendars, 2009-10 to 2025-26; South Carolina Department of Education missed-day reports, 2021-22 to 2024-25.