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San Joaquin County Climate

San Joaquin County, California

NOAA NCEI 1991-2020 Climate Normals
JanFebMarAprMayJunJulAugSepOctNovDec62.5°AVG °F

Avg Annual Temp

62.5°F

Annual Precip

15.9"

Annual Snowfall

0.0"

Extreme Heat Days

84

days >= 90°F/yr

Monthly Temperature

54.4°F avgJFMAMJJASOND

Precipitation Calendar

Dry
Wet= snowfall
3.1"
3.0"
2.2"
1.3"
0.7"
0.1"
0.0"
0.0"
0.1"
0.8"
1.6"
3.0"
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Growing Season & Gardening

USDA Hardiness Zone

9b

Minimum winter temperature range for plant survival

Growing Degree Days

4,856

Excellent for heat-loving crops

Last spring frost (32°F): 02/09
First fall frost (32°F): 12/05

Seasonal Overview

Comfort ZoneSpring56°67°4.2"Summer73°77°0.2"Fall55°73°2.5"Winter48°52°9.1"20°40°60°80°100°

National Comparison

Warmer than 80% of US counties
Wetter than 8% of US counties
More seasonal variation than 4% of US counties

7-Day Outlook

Forecast

Current Conditions

Air Quality

Safety

Weather Alerts

Climate Advisory: San Joaquin County

Climate Verdict

San Joaquin County has a warm, averaging 62.5°F year-round, semi-arid conditions with only 15.9 inches of annual precipitation, significant summer heat with 83.875 days annually above 90°F, virtually no measurable snowfall. This climate profile shapes everything from energy costs to outdoor recreation opportunities.

Seasonal Breakdown

Winters are mild, with January temperatures averaging 47.9°F. summers are warm — July averages 76.6°F. The climate is remarkably stable year-round, with only a 29°F difference between January and July. December is typically the coldest month and July the warmest.

Outdoor & Gardening Guidance

Summer outdoor activities should be planned for early morning or evening to avoid extreme heat.

Regional Context

San Joaquin County is 3.9°F warmer than the California statewide average of 58.7°F, it is also noticeably drier, receiving 9.8 inches less precipitation than the state average, the county experiences 25.204075037066126 more extreme heat days than the state average.

Climate Profile

About San Joaquin County Weather

Warm and dry in San Joaquin

San Joaquin County averages 62.5°F, making it warmer than the U.S. median. The region is relatively dry, with only 15.9 inches of annual precipitation.

A typical Central Valley profile

The county's 62.5°F average is higher than the California state average of 58.7°F. Its precipitation of 15.9 inches is significantly below the state average of 25.8 inches.

Mirroring the Sacramento climate

San Joaquin is nearly identical to Sacramento County in temperature and rainfall. Both counties experience the same 75.2°F summer average and zero annual snowfall.

Hot summers and foggy winters

There are 84 extreme heat days per year, with July averages reaching 76.6°F. Winters are cool and damp, averaging 47.9°F in January with no recorded snowfall.

Prepare for significant summer heat

Reliable AC is a must for the 84 days of 90-plus degree weather. Residents should also prepare for winter tule fog which often accompanies the cool 49.2°F winter average.

Frequently Asked Questions

What is the average temperature in San Joaquin County?
The average annual temperature in San Joaquin County, CA is 62.5°F, based on NOAA 30-year climate normals (1991-2020).
How much rain does San Joaquin County get?
San Joaquin County receives an average of 15.9 inches of precipitation per year, including both rain and meltwater from snow. This is based on NOAA 30-year climate normals.
Does it snow in San Joaquin County?
San Joaquin County receives little to no measurable snowfall in a typical year, based on NOAA 30-year climate normals.
How hot does San Joaquin County get in summer?
The average summer temperature (June-August) in San Joaquin County is 75.2°F. The county experiences an average of 84 days per year above 90°F.
How cold are winters in San Joaquin County?
The average winter temperature (December-February) in San Joaquin County is 49.2°F. January, typically the coldest month, averages 47.9°F.

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Data sources: NOAA National Centers for Environmental Information (NCEI), U.S. Climate Normals 1991-2020. Forecast and alert data from National Weather Service API. Air quality data from Open-Meteo.

Climate normals are 30-year averages of weather variables. Station data is aggregated to county level. Forecasts and alerts are fetched live and may change frequently. Data is informational only — not a substitute for official National Weather Service forecasts or emergency weather warnings.

By Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, Data Editor
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