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.

Tonight

56°F

Mostly Clear

Mostly clear. Low around 56, with temperatures rising to around 58 overnight. South southwest wind around 7 mph.

7-day forecast for Castle Hill

When	Temp	Forecast	Wind	Precip
Tonight	56°F	Mostly Clear	7 mph SSW	0%
Saturday	87°F	Sunny	3 to 7 mph SW	0%
Saturday Night	57°F	Partly Cloudy	7 mph SSW	0%
Sunday	78°F	Partly Sunny	8 mph SW	3%
Sunday Night	56°F	Mostly Cloudy	8 mph SW	3%
Monday	80°F	Mostly Sunny	6 to 9 mph WSW	0%
Monday Night	56°F	Mostly Clear	5 to 9 mph SW	0%
Tuesday	84°F	Sunny	3 to 7 mph WSW	0%
Tuesday Night	57°F	Mostly Clear	1 to 7 mph SW	0%
Wednesday	95°F	Sunny	0 to 5 mph WSW	0%
Wednesday Night	62°F	Mostly Clear	1 to 5 mph SW	0%
Thursday	96°F	Sunny	0 to 7 mph WSW	0%
Thursday Night	62°F	Mostly Clear	3 to 7 mph WSW	0%
Friday	88°F	Sunny	3 to 7 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

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.