Bethel Island, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Bethel Island, a community in Contra Costa County, California.
This Afternoon
87°F
Sunny
Sunny, with a high near 87. West northwest wind around 9 mph.
7-day forecast for Bethel Island
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 87°F | Sunny | 9 mph WNW | 0% |
| Tonight | 59°F | Partly Cloudy | 2 to 9 mph W | 0% |
| Sunday | 81°F | Partly Sunny | 5 to 8 mph W | 0% |
| Sunday Night | 58°F | Mostly Cloudy | 8 mph W | 0% |
| Monday | 83°F | Sunny | 7 to 10 mph W | 0% |
| Monday Night | 58°F | Mostly Clear | 3 to 10 mph WSW | 0% |
| Tuesday | 83°F | Sunny | 3 to 9 mph W | 0% |
| Tuesday Night | 59°F | Mostly Clear | 1 to 9 mph W | 0% |
| Wednesday | 89°F | Sunny | 1 to 6 mph WNW | 0% |
| Wednesday Night | 62°F | Mostly Clear | 1 to 6 mph W | 0% |
| Thursday | 92°F | Sunny | 1 to 7 mph WNW | 0% |
| Thursday Night | 63°F | Mostly Clear | 7 mph W | 0% |
| Friday | 87°F | Sunny | 5 to 12 mph W | 0% |
| Friday Night | 61°F | Mostly Clear | 7 to 12 mph WSW | 0% |
Forecast source: National Weather Service (api.weather.gov) for Bethel Island (38.028, -121.630). Updated through the day.
Growing snapshot for Bethel Island
Last spring frost
Jan 12
First fall frost
Dec 19
Growing season
343 days
Hardiness zone
9b
More local growing data for Bethel Island: nearby ZIP 94511 weather · frost dates · planting calendar · California frost dates
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Climate data from the nearest NOAA station, Antioch Pumping Plt #3, Ca (7.4 mi from Bethel Island). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 20, 2026.