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Weather & Climate in Discovery Bay, CA

Temperature, precipitation, air quality, natural hazards, and monthly weather data.

Discovery Bay enjoys a temperate climate with an average annual temperature of 64°F (18°C). Winters average 48°F in January while summers reach 78°F in July. The area gets 330 sunny days per year, well above the U.S. average of 205 / making it one of the sunnier locations in the country. Annual precipitation totals 12.4 inches (drier than the 38-inch national average). Air quality is rated Good with a median AQI of 48. The city sits at an elevation of 1 feet.

Temperature

48°F Jan (9°C) 78°F Jul (25°C)
Annual Average63.5°F
18% above US avg
January Average48°F (9°C)
July Average78°F (25°C)
Sunny Days330 days/yr

Geography

Elevation1 ft (0 m)
Area5.6 sq mi (14.5 km²)
Population Density2,727/sq mi
Coordinates37.9081°N, 121.5972°W
TimezoneAmerica/Los_Angeles
CountySan Joaquin County County
Nearest AirportMetro Oakland International (OAK)
36 miles away

Precipitation & Snow

Annual Rainfall 12.4"
67% below US avg
Snowfall 0.0"
Wettest Month (Jan) 2.52"
Driest Month (Jul) 0.04"

Air Quality

AQI Median48.0
RatingGood

Natural Hazard Risk

Overall RiskRelatively High
Risk Score98.6 / 100
Social Vulnerability39.7 / 100
Community Resilience47.0 / 100

Hazard Breakdown

Tornado Relatively Low
Earthquake Relatively High
Wildfire Relatively Moderate
Flood Relatively High
Hail Relatively Low
Strong Wind Relatively Low
Heat Wave Relatively High
Winter Weather Relatively Low
Lightning Relatively High
Drought Very High
Cold Wave No Rating
Landslide Very Low
Volcano Very Low
Avalanche Very Low
Source: FEMA National Risk Index v1.20 (Dec 2025)

Earthquake History

5,766 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M6.0.

Aug 24, 2014 The 2014 South Napa, California Earthquake M6.0 71 km 11 km
Apr 18, 1990 5 km NNW of Aromas, California M5.4 109 km 5 km
Apr 18, 1990 4 km E of Interlaken, California M5.1 106 km 7 km
Aug 12, 1998 10 km SW of Ridgemark, California M5.1 129 km 9 km
Jan 16, 1993 9 km E of Gilroy, California M4.9 100 km 7 km
Apr 18, 1990 4 km NNW of Aromas, California M4.9 109 km 6 km
Apr 23, 1995 22 km NNE of Soledad, California M4.9 149 km 7 km
Apr 19, 1996 2 km E of Aromas, California M4.9 114 km 5 km
May 14, 2002 5 km SSW of Gilroy, California M4.9 105 km 7 km
Sep 3, 2000 5 km WSW of Yountville, California M4.9 89 km 9 km
Sep 4, 1995 13 km SW of Middletown, California M4.8 132 km 7 km
May 12, 2006 7 km W of Cobb, California M4.7 147 km 4 km
May 21, 1996 8 km ESE of East Foothills, California M4.7 62 km 8 km
Apr 18, 1990 4 km N of Aromas, California M4.7 109 km 4 km
Aug 11, 1993 14 km ESE of Alum Rock, California M4.7 67 km 9 km
Jan 2, 2025 4 km NW of Cobb, CA M4.7 145 km 1 km
Mar 24, 1991 1 km NNE of Interlaken, California M4.6 106 km 15 km
Aug 18, 1999 0 km S of Bolinas, California M4.6 96 km 8 km
Jan 11, 2000 6 km N of Geyserville, California M4.6 150 km 6 km
Feb 18, 2004 4 km WNW of Cobb, California M4.6 145 km 3 km
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.

Tornado History

82 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2. Total: 5 injuries.

Date Rating Distance Path Fatalities
May 5, 1998 EF2 71 km 0.6 mi 0
Feb 7, 1978 EF2 89 km 1.9 mi 0
Apr 27, 1953 EF2 60 km 0.1 mi 0
Jan 11, 1951 EF2 76 km 5.7 mi 0
Mar 11, 2023 EF1 94 km 0.8 mi 0
Jan 10, 2023 EF1 76 km 0.4 mi 0
Dec 24, 2015 EF1 98 km 6.2 mi 0
Nov 15, 2015 EF1 81 km 3.0 mi 0
Jan 23, 2010 EF1 15 km 1.6 mi 0
Apr 14, 2006 EF1 60 km 0.5 mi 0
Mar 20, 2005 EF1 78 km 3.0 mi 0
May 5, 1998 EF1 75 km 0.3 mi 0
Dec 12, 1996 EF1 67 km 0.6 mi 0
Apr 19, 1988 EF1 49 km 0.2 mi 0
Apr 19, 1988 EF1 94 km 1.0 mi 0
Mar 22, 1983 EF1 93 km 2.0 mi 0
Jan 14, 1980 EF1 54 km 0.3 mi 0
Mar 4, 1978 EF1 85 km 1.0 mi 0
Mar 4, 1978 EF1 74 km 2.5 mi 0
Mar 1, 1978 EF1 64 km 1.5 mi 0
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).

Tsunami History

5 tsunamis recorded within 500 km. Highest wave on record: 4.5 m (15 ft).

Year Location Cause Max Wave Deaths Distance
1868 N. CALIFORNIA Eruption + Earthquake 4.5 m 30 50 km
1989 N. CALIFORNIA Earthquake 1.0 m 62 100 km
1856 N. CALIFORNIA Eruption + Earthquake 0.6 m — 77 km
1906 N. CALIFORNIA Eruption + Earthquake 0.1 m — 83 km
1865 N. CALIFORNIA Eruption + Earthquake — — 83 km
Source: NOAA/NCEI Historical Tsunami Database.

Nearby Volcanoes

1 volcano within 200 km. Closest: Clear Lake (156 km).

Name Type Elevation Last Eruption Distance
Clear Lake Volcanic field 1,439 m (4,721 ft) Unknown 156 km
Source: Smithsonian Institution Global Volcanism Program (GVP).

Wildfire History

20 wildfires (100+ acres) recorded within 100 km. Largest: SCU LIGHTNING COMPLEX (405,787 acres, 2020).

Year Name Acres Burned Distance
2020 SCU LIGHTNING COMPLEX 405,787 47 km
2020 HENNESSEY 314,241 100 km
2018 COUNTY 92,450 99 km
2015 BUTTE 72,894 97 km
2017 NUNS 56,883 93 km
2017 ATLAS 51,664 76 km
2007 LICK 47,424 78 km
2006 CANYON 36,851 65 km
1988 MILLER 35,750 73 km
2003 ANNIE 17,383 82 km
2024 CORRAL 16,138 33 km
2006 ZAM ASSIST 14,404 98 km
2018 WAVERLY 12,238 67 km
2009 CORRAL 12,006 36 km
1985 LEXINGTON 11,550 89 km
1996 SCOTT 8,828 87 km
2015 WRAGG 8,455 76 km
2003 BIRD 7,727 46 km
2014 MONTICELLO 6,984 81 km
1984 SITE 300 3 6,911 31 km
Source: NIFC/IRWIN Wildfire Records (100+ acres).

Monthly Weather

Month Avg Temperature Precipitation Summary
January 48°F (9°C) 2.5 in Wettest
February 51°F (11°C) 2.1 in
March 55°F (13°C) 1.7 in
April 59°F (15°C) 0.8 in
May 65°F (18°C) 0.3 in
June 70°F (21°C) 0.1 in
July 78°F (25°C) 0.0 in Warmest, Driest
August 73°F (23°C) 0.1 in
September 70°F (21°C) 0.2 in
October 64°F (18°C) 0.8 in
November 54°F (12°C) 1.8 in
December 46°F (8°C) 1.8 in Coldest

Discovery Bay has a seasonal temperature swing of 32°F / from 46°F in December to 78°F in July. Total annual precipitation is 12.3 inches, with January being the wettest month (2.5") and July the driest (0.0").

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