Castle Hill, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Castle Hill, a community in Contra Costa County, California.
Overnight
56°F
Mostly Clear
Mostly clear. Low around 56, with temperatures rising to around 58 overnight. South wind around 5 mph.
7-day forecast for Castle Hill
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 56°F | Mostly Clear | 5 mph S | 0% |
| Saturday | 87°F | Sunny | 3 to 8 mph SW | 0% |
| Saturday Night | 56°F | Partly Cloudy | 7 mph SW | 0% |
| Sunday | 77°F | Mostly Cloudy | 7 mph SW | 3% |
| Sunday Night | 56°F | Mostly Cloudy | 7 mph SW | 3% |
| Monday | 79°F | Sunny | 6 to 9 mph SW | 0% |
| Monday Night | 56°F | Mostly Clear | 5 to 9 mph SW | 0% |
| Tuesday | 82°F | Sunny | 7 mph WSW | 0% |
| Tuesday Night | 56°F | Mostly Clear | 2 to 7 mph SW | 0% |
| Wednesday | 93°F | Sunny | 1 to 5 mph WSW | 0% |
| Wednesday Night | 60°F | Mostly Clear | 1 to 5 mph SW | 0% |
| Thursday | 94°F | Sunny | 1 to 7 mph WSW | 0% |
| Thursday Night | 60°F | Mostly Clear | 3 to 7 mph WSW | 0% |
| Friday | 86°F | Sunny | 5 to 8 mph SW | 0% |
Forecast source: National Weather Service (api.weather.gov) for Castle Hill (37.875, -122.059). Updated through the day.
Growing snapshot for Castle Hill
Last spring frost
Mar 8
First fall frost
Dec 22
Growing season
282 days
Hardiness zone
9b
More local growing data for Castle Hill: nearby ZIP 94595 weather · frost dates · planting calendar · California frost dates
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Climate data from the nearest NOAA station, Mt Diablo Junction, Ca (7.6 mi from Castle Hill). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.