Snow Day Predictor for Rialto, CA

Rialto is a mid-size city of about 103,132 people that sits well south, where snow is a rarer visitor, near 34.1°N in California. A winter here typically brings usually only a few inches a year in the lowlands. When snow does fall, it has an outsized effect on a region built for rain. Because the town falls in the Pacific lowland climate region, our model's closure threshold for Rialto is tuned to close fairly easily, since snow-clearing equipment here is limited and roads ice quickly.

The percentage at the top of this page isn't a static guess — it's rebuilt each night from Rialto's own Open-Meteo forecast. The model reads seven signals from the overnight-into-morning window: total snowfall, whether any of it is timed for the 2–6 a.m. commute, freezing rain or sleet, the coldest air temperature, the wind chill, the peak wind, and how much snow is already on the ground. Snow is rare and equipment is limited, so even 1–2" or any ice can close or delay schools. A dusting that would be ignored back east often triggers a delay here.

Because a 2-hour delay clears a lower bar than an outright cancellation, you'll often see delay odds for Rialto even when the closure odds stay modest — that gap is the model flagging a borderline morning. The estimate shifts as the forecast firms up overnight, so it's worth re-checking Rialto's odds the evening before school. Treat it as a well-informed second opinion for planning, never as an official California closing announcement.