Alum Rock, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Alum Rock, a community in Santa Clara County, California.
Overnight
49°F
Mostly Clear
Mostly clear, with a low around 49. Northeast wind around 2 mph.
7-day forecast for Alum Rock
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 49°F | Mostly Clear | 2 mph NE | 0% |
| Wednesday | 68°F | Patchy Fog then Sunny | 2 to 9 mph NNW | 1% |
| Wednesday Night | 50°F | Mostly Cloudy | 2 to 7 mph NNE | 1% |
| Thursday | 73°F | Patchy Fog then Mostly Sunny | 2 to 7 mph N | 0% |
| Thursday Night | 49°F | Clear | 5 mph NNE | 0% |
| Friday | 75°F | Sunny | 5 mph NNE | 0% |
| Friday Night | 52°F | Mostly Clear | 0 to 5 mph NE | 0% |
| Saturday | 78°F | Sunny | 0 to 3 mph NE | 0% |
| Saturday Night | 52°F | Mostly Clear | 0 to 3 mph N | 0% |
| Sunday | 77°F | Sunny | 0 to 5 mph NNW | 0% |
| Sunday Night | 52°F | Partly Cloudy | 0 to 5 mph N | 0% |
| Monday | 74°F | Mostly Sunny | 0 to 6 mph NNW | 0% |
| Monday Night | 52°F | Partly Cloudy | 1 to 6 mph N | 1% |
| Tuesday | 74°F | Sunny | 0 to 5 mph NNW | 4% |
Forecast source: National Weather Service (api.weather.gov) for Alum Rock (37.369, -121.824). Updated through the day.
Growing snapshot for Alum Rock
Last spring frost
Jan 2
First fall frost
Dec 25
Growing season
362 days
Hardiness zone
9b
More local growing data for Alum Rock: nearby ZIP 95116 weather · frost dates · planting calendar · California frost dates
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Climate data from the nearest NOAA station, San Jose, Ca (2.8 mi from Alum Rock). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.