San Geronimo, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for San Geronimo, a community in Marin County, California.
This Afternoon
75°F
Sunny
Sunny. High near 75, with temperatures falling to around 70 in the afternoon. West northwest wind 6 to 9 mph, with gusts as high as 18 mph.
7-day forecast for San Geronimo
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 75°F | Sunny | 6 to 9 mph WNW | 0% |
| Tonight | 54°F | Mostly Clear | 2 to 8 mph WNW | 0% |
| Saturday | 78°F | Patchy Fog then Sunny | 2 to 8 mph WNW | 0% |
| Saturday Night | 54°F | Partly Cloudy | 5 to 8 mph WNW | 0% |
| Sunday | 71°F | Partly Sunny | 5 to 8 mph W | 0% |
| Sunday Night | 54°F | Mostly Cloudy | 2 to 8 mph W | 0% |
| Monday | 71°F | Mostly Sunny | 2 to 7 mph WSW | 0% |
| Monday Night | 54°F | Partly Cloudy | 2 to 7 mph WSW | 0% |
| Tuesday | 74°F | Patchy Fog then Sunny | 2 to 7 mph WSW | 0% |
| Tuesday Night | 53°F | Mostly Clear | 1 to 7 mph W | 0% |
| Wednesday | 83°F | Patchy Fog then Sunny | 1 to 7 mph SE | 0% |
| Wednesday Night | 58°F | Mostly Clear | 1 to 7 mph W | 0% |
| Thursday | 83°F | Sunny | 1 to 7 mph SW | 0% |
| Thursday Night | 58°F | Partly Cloudy | 2 to 7 mph W | 0% |
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 Sep 18, 2026.