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.
Today
100°F
Sunny
Sunny. High near 100, with temperatures falling to around 96 in the afternoon. Southwest wind 5 to 8 mph.
7-day forecast for Castle Hill
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 100°F | Sunny | 5 to 8 mph SW | 0% |
| Tonight | 58°F | Clear | 5 to 8 mph SW | 0% |
| Wednesday | 94°F | Sunny | 5 to 8 mph SW | 0% |
| Wednesday Night | 59°F | Clear | 5 to 8 mph WSW | 0% |
| Thursday | 91°F | Sunny | 3 to 8 mph WSW | 0% |
| Thursday Night | 60°F | Clear | 5 to 8 mph WSW | 0% |
| Friday | 96°F | Sunny | 3 to 8 mph WSW | 0% |
| Friday Night | 62°F | Clear | 5 to 8 mph SW | 0% |
| Saturday | 96°F | Sunny | 3 to 8 mph WSW | 0% |
| Saturday Night | 63°F | Mostly Clear | 8 mph SW | 0% |
| Sunday | 90°F | Sunny | 6 to 10 mph SW | 0% |
| Sunday Night | 59°F | Mostly Clear | 10 mph SW | 0% |
| Monday | 84°F | Sunny | 8 to 12 mph SW | 0% |
| Monday Night | 58°F | Mostly Clear | 7 to 12 mph WSW | 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 Aug 4, 2026.