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Measurable snow is rare in Napa: the 1991–2020 normal rounds to zero — only a trace in most years, and nights reach freezing on about 34 days a year. When snow or ice does arrive, it causes outsized trouble because roads are rarely treated — watch for Winter Weather Advisories and Freeze Warnings.
| Month | Snowfall | Days 1″+ | Days with snow cover | Freezing nights | Avg. low |
|---|---|---|---|---|---|
| November | 0″ | 0 | 0 | 5 | 40°F |
| December | 0″ | 0 | 0 | 11 | 38°F |
| January | 0″ | 0 | 0 | 9 | 38°F |
| February | 0″ | 0 | 0 | 5 | 40°F |
| March | 0″ | 0 | 0 | 2 | 42°F |
| April | 0″ | 0 | 0 | 1 | 44°F |
| Year | 0″ | 0 | 0 | 34 |
NOAA NCEI U.S. Climate Normals 1991–2020 — snowfall at Napa State Hospital (2 mi from the city center, +7 ft elevation difference); temperatures at Napa Co Airport. Averages smooth out big years: single winters can bring half or double the normal.
All California winter alerts and cities → · National winter storm map → · Frost dates by ZIP code →
0 inches in an average year (NOAA U.S. Climate Normals 1991–2020, Napa State Hospital station, 2 miles away).
This page checks the National Weather Service for active alerts at Napa's location every time you open it; the box at the top lists any winter storm, winter weather, cold or freeze alert in effect right now.
About 34 nights a year drop to 32 °F or below (NOAA 1991–2020); the coldest month, December, averages a low of 38 °F.