Contra Costa County Climate
Contra Costa County, California
Avg Annual Temp
60.4°F
Annual Precip
19.4"
Annual Snowfall
0.1"
Extreme Heat Days
40.11666666666667
days >= 90°F/yr
Monthly Temperature
Precipitation Calendar
Seasonal Overview
National Comparison
Climate Profile
About Contra Costa County Weather
A Warm and Steady Bay Climate
Contra Costa County averages 60.4°F, putting it comfortably above the median temperature for the United States. Its weather is characterized by mild winters and warm, dry summers.
Warmer and Drier Than State Averages
The county is warmer than the California average of 58.7°F. Its 19.4 inches of annual precipitation is about 6 inches lower than the state's 25.8-inch average.
Warmer and Drier than Alameda
Contra Costa is slightly warmer and drier than its neighbor Alameda County. While Alameda receives 18.1 inches of rain, Contra Costa receives 19.4 but has 14 more extreme heat days.
Forty Days of Heat and Zero Snow
July averages 71.3°F, contributing to 40 extreme heat days each year. Winter is very mild at 49.6°F with virtually no snow recorded annually.
Invest in Cooling for 40 Heatwaves
Air conditioning is essential for the 40 days of temperatures over 90°F. Because snow is non-existent, residents should prioritize summer gear and water-efficient landscaping.
Frequently Asked Questions
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Track your own weather in Contra Costa County
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Data source: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020.
Climate normals are 30-year averages of weather variables computed from 1991 to 2020. Station data is aggregated to county level using spatial averaging. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.