San Geronimo, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for San Geronimo, a community in Marin County, California.
Tonight
48°F
Partly Cloudy
Partly cloudy. Low around 48, with temperatures rising to around 50 overnight. East wind around 6 mph.
7-day forecast for San Geronimo
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 48°F | Partly Cloudy | 6 mph E | 8% |
| Wednesday | 63°F | Sunny | 3 to 9 mph NNE | 2% |
| Wednesday Night | 50°F | Mostly Cloudy | 5 to 8 mph NW | 2% |
| Thursday | 68°F | Mostly Sunny | 5 mph NW | 0% |
| Thursday Night | 48°F | Mostly Clear | 5 mph NNW | 0% |
| Friday | 69°F | Sunny | 5 mph N | 0% |
| Friday Night | 50°F | Mostly Clear | 0 to 5 mph NNW | 0% |
| Saturday | 71°F | Sunny | 1 to 5 mph NE | 0% |
| Saturday Night | 50°F | Mostly Clear | 3 mph NW | 0% |
| Sunday | 68°F | Mostly Sunny | 5 mph NW | 0% |
| Sunday Night | 52°F | Partly Cloudy | 5 mph NW | 0% |
| Monday | 66°F | Mostly Sunny | 2 to 6 mph NW | 2% |
| Monday Night | 51°F | Partly Cloudy | 2 to 6 mph NW | 2% |
| Tuesday | 66°F | Sunny | 5 mph NNW | 8% |
Forecast source: National Weather Service (api.weather.gov) for San Geronimo (38.007, -122.663). Updated through the day.
Growing snapshot for San Geronimo
Last spring frost
Jan 11
First fall frost
Dec 21
Growing season
349 days
Hardiness zone
9b
More local growing data for San Geronimo: nearby ZIP 94963 weather · frost dates · planting calendar · California frost dates
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Climate data from the nearest NOAA station, San Rafael Civic Ctr, Ca (7 mi from San Geronimo). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.