Contra Costa County weather, town by town
53 places in Contra Costa County, California, each with its own live forecast and radar, and where a station sits close enough, measured weather records.
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Measured at the NOAA stations serving these towns, daily records 1893 to 2026. Station extremes, not official state records.
Contra Costa County Weather Facts
Contra Costa County has 53 places on myweatherrock (34 census-designated places, 17 cities, 2 towns), each with its own live forecast, hourly timeline, ten day outlook and radar. The hottest day in the station records is 113°F at Vallejo on September 1, 2017. The coldest night is 14°F at Mt Diablo Junction on February 6, 1989. The wettest day brought 6.83 inches of rain at Richmond on January 4, 1982. The biggest single-day snow measured 7.99 inches at Mt Diablo Junction on March 14, 1975. Those are station measurements from NOAA's daily records, 1893 to 2026, not official state records. By area the largest place is Concord, about 31 square miles.
About Contra Costa County weather
The map on the Now tab shows every Contra Costa County town's current temperature from our own server, one dot per town. Tap any dot, or type a town above, for that town's full forecast.
What the weather is usually like
Across the 53 Contra Costa County towns with station normals, the warmest month is July, when the day usually reaches 83°F, and the coldest is January, when the night usually falls to 41°F. January is the wettest, with rain on about 10 days. July afternoons run from about 71°F in Bayview to 94°F in Bethel Island. January nights run from about 40°F in Acalanes Ridge to 44°F in Bayview.
Means of the 1991 to 2020 station normals serving these towns, as published by NOAA; each town's page carries its own.
Where these numbers come from
- Current conditions and forecast: NOAA forecast grids decoded on our own server, corrected against the nearest reporting station and our own radar. Open-Meteo is consulted only as a fallback when our server is silent.
- Records: computed by myweatherrock from NOAA GHCN-Daily station records at the stations serving these towns. Measurements, not estimates.
- Warnings and alerts: the National Weather Service, passed through unchanged.
Contra Costa County weather records
Measured at the NOAA stations serving these towns, daily records 1893 to 2026. Station extremes, not official state records.
Common questions about Contra Costa County weather
- What is the hottest temperature recorded at a Contra Costa County station?
- 113°F at Vallejo on September 1, 2017, in the NOAA daily station records myweatherrock holds (1893 to 2026).
- What is the coldest temperature recorded at a Contra Costa County station?
- 14°F at Mt Diablo Junction on February 6, 1989.
- What is the most rain a Contra Costa County station has measured in one day?
- 6.83 inches at Richmond on January 4, 1982.
- What is the biggest one-day snowfall at a Contra Costa County station?
- 7.99 inches at Mt Diablo Junction on March 14, 1975.
- How many Contra Costa County towns have a weather page here?
- 53: 34 census-designated places, 17 cities, 2 towns. Each page carries current conditions, the hourly timeline, the ten day outlook, radar, and where a station sits close enough, measured records.
- Where does the Contra Costa County forecast come from?
- NOAA forecast grids (the National Weather Service digital forecast, the National Blend of Models, HRRR and GFS) decoded on our own server, corrected against the nearest reporting station and our own radar. Open-Meteo is consulted only as a fallback when our server is silent.
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