Diablo, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Diablo, a community in Contra Costa County, California.
Tonight
55°F
Mostly Clear
Mostly clear, with a low around 55. South southeast wind around 5 mph.
7-day forecast for Diablo
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 55°F | Mostly Clear | 5 mph SSE | 0% |
| Saturday | 89°F | Sunny | 2 to 6 mph SSW | 0% |
| Saturday Night | 56°F | Mostly Cloudy | 6 mph SW | 0% |
| Sunday | 79°F | Partly Sunny | 6 mph SW | 3% |
| Sunday Night | 55°F | Mostly Cloudy | 3 to 7 mph SW | 3% |
| Monday | 82°F | Mostly Sunny | 7 mph WSW | 0% |
| Monday Night | 55°F | Mostly Clear | 2 to 7 mph WSW | 0% |
| Tuesday | 86°F | Sunny | 2 to 6 mph WSW | 0% |
| Tuesday Night | 56°F | Mostly Clear | 0 to 6 mph SW | 0% |
| Wednesday | 97°F | Sunny | 0 to 3 mph W | 0% |
| Wednesday Night | 61°F | Mostly Clear | 0 to 3 mph W | 0% |
| Thursday | 97°F | Sunny | 0 to 6 mph WSW | 0% |
| Thursday Night | 60°F | Mostly Clear | 1 to 6 mph WSW | 0% |
| Friday | 90°F | Sunny | 2 to 6 mph SW | 0% |
Forecast source: National Weather Service (api.weather.gov) for Diablo (37.841, -121.956). Updated through the day.
Growing snapshot for Diablo
Last spring frost
Mar 8
First fall frost
Dec 22
Growing season
282 days
Hardiness zone
9b
More local growing data for Diablo: nearby ZIP 94528 weather · frost dates · planting calendar · California frost dates
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Climate data from the nearest NOAA station, Mt Diablo Junction, Ca (3 mi from Diablo). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.