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Weather & Climate in San Miguel CDP (Contra Costa County), CA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
San Miguel CDP (Contra Costa County) enjoys a temperate climate with an average annual temperature of 62°F (17°C). Winters average 50°F in January while summers reach 73°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 17.7 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 262 feet.
Temperature
50°F Jan (10°C)
73°F Jul (23°C)
| Annual Average | 62.4°F |
| 16% above US avg | |
| January Average | 50°F (10°C) |
| July Average | 73°F (23°C) |
| Sunny Days | 330 days/yr |
Geography
| Elevation | 262 ft (80 m) |
| Area | 1.1 sq mi (2.7 km²) |
| Population Density | 3,801/sq mi |
| Coordinates | 37.8867°N, 122.0368°W |
| Timezone | America/Los_Angeles |
| County | San Mateo County County |
| Nearest Airport | Metro Oakland International (OAK) 15 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 48.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Relatively High |
| Risk Score | 99.2 / 100 |
| Social Vulnerability | 20.5 / 100 |
| Community Resilience | 97.6 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Earthquake | Relatively High |
| Wildfire | Relatively Moderate |
| Flood | Relatively High |
| Hail | Very Low |
| Strong Wind | Relatively Low |
| Heat Wave | Relatively Moderate |
| Winter Weather | Very Low |
| Lightning | Relatively Moderate |
| Drought | Relatively High |
| Cold Wave | No Rating |
| Landslide | Relatively High |
| Coastal Flood | Relatively High |
| Tsunami | Relatively Moderate |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
5,363 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 | 44 km | 11 km |
| Apr 18, 1990 | 5 km NNW of Aromas, California | M5.4 | 111 km | 5 km |
| Aug 12, 1998 | 10 km SW of Ridgemark, California | M5.1 | 136 km | 9 km |
| Apr 18, 1990 | 4 km E of Interlaken, California | M5.1 | 108 km | 7 km |
| Jan 16, 1993 | 9 km E of Gilroy, California | M4.9 | 109 km | 7 km |
| Apr 18, 1990 | 4 km NNW of Aromas, California | M4.9 | 112 km | 6 km |
| Sep 3, 2000 | 5 km WSW of Yountville, California | M4.9 | 64 km | 9 km |
| Apr 19, 1996 | 2 km E of Aromas, California | M4.9 | 118 km | 5 km |
| May 14, 2002 | 5 km SSW of Gilroy, California | M4.9 | 109 km | 7 km |
| Sep 4, 1995 | 13 km SW of Middletown, California | M4.8 | 108 km | 7 km |
| May 12, 2006 | 7 km W of Cobb, California | M4.7 | 124 km | 4 km |
| May 21, 1996 | 8 km ESE of East Foothills, California | M4.7 | 65 km | 8 km |
| Apr 18, 1990 | 4 km N of Aromas, California | M4.7 | 112 km | 4 km |
| Aug 11, 1993 | 14 km ESE of Alum Rock, California | M4.7 | 71 km | 9 km |
| Jan 2, 2025 | 4 km NW of Cobb, CA | M4.7 | 124 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 | 57 km | 8 km |
| Jan 11, 2000 | 6 km N of Geyserville, California | M4.6 | 124 km | 6 km |
| Feb 18, 2004 | 4 km WNW of Cobb, California | M4.6 | 123 km | 3 km |
| Jan 12, 2014 | 8 km W of Cobb, California | M4.5 | 123 km | 2 km |
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
69 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2. Total: 9 injuries.
| Date | Rating | Distance | Path | Fatalities |
| May 5, 1998 | EF2 | 58 km | 0.6 mi | 0 |
| Jun 1, 1958 | EF2 | 93 km | 15.0 mi | 0 |
| Apr 27, 1953 | EF2 | 95 km | 0.1 mi | 0 |
| Jan 11, 1951 | EF2 | 58 km | 5.7 mi | 0 |
| Dec 14, 2024 | EF1 | 93 km | 0.3 mi | 0 |
| Mar 18, 2011 | EF1 | 86 km | 0.1 mi | 0 |
| Jan 23, 2010 | EF1 | 24 km | 1.6 mi | 0 |
| Apr 14, 2006 | EF1 | 95 km | 0.5 mi | 0 |
| Mar 20, 2005 | EF1 | 43 km | 3.0 mi | 0 |
| Dec 5, 1998 | EF1 | 85 km | 1.5 mi | 0 |
| May 5, 1998 | EF1 | 57 km | 0.3 mi | 0 |
| Dec 23, 1996 | EF1 | 88 km | 6.0 mi | 0 |
| Feb 22, 1996 | EF1 | 95 km | 1.0 mi | 0 |
| Dec 2, 1992 | EF1 | 95 km | 7.5 mi | 0 |
| Dec 2, 1992 | EF1 | 90 km | 1.0 mi | 0 |
| Apr 19, 1988 | EF1 | 84 km | 0.2 mi | 0 |
| Feb 27, 1983 | EF1 | 85 km | 0.8 mi | 0 |
| Jan 14, 1980 | EF1 | 47 km | 0.3 mi | 0 |
| May 31, 1967 | EF1 | 65 km | 0.1 mi | 0 |
| Nov 10, 1964 | EF1 | 98 km | 1.0 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 | 22 km |
| 1989 | N. CALIFORNIA | Earthquake | 1.0 m | 62 | 96 km |
| 1856 | N. CALIFORNIA | Eruption + Earthquake | 0.6 m | — | 49 km |
| 1906 | N. CALIFORNIA | Eruption + Earthquake | 0.1 m | — | 46 km |
| 1865 | N. CALIFORNIA | Eruption + Earthquake | — | — | 77 km |
Source: NOAA/NCEI Historical Tsunami Database.
Nearby Volcanoes
1 volcano within 200 km. Closest: Clear Lake (136 km).
| Name | Type | Elevation | Last Eruption | Distance |
| Clear Lake | Volcanic field | 1,439 m (4,721 ft) | Unknown | 136 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 | 64 km |
| 2020 | HENNESSEY | 314,241 | 85 km |
| 2018 | COUNTY | 92,450 | 89 km |
| 2020 | CZU AUG LIGHTNING | 85,894 | 84 km |
| 2020 | GLASS | 68,020 | 86 km |
| 2017 | NUNS | 56,883 | 66 km |
| 2017 | ATLAS | 51,664 | 56 km |
| 2007 | LICK | 47,424 | 91 km |
| 2004 | RUMSEY | 39,335 | 99 km |
| 2017 | TUBBS | 36,981 | 94 km |
| 2006 | CANYON | 36,851 | 85 km |
| 1988 | MILLER | 35,750 | 61 km |
| 2024 | CORRAL | 16,138 | 58 km |
| 2006 | ZAM ASSIST | 14,404 | 97 km |
| 2009 | CORRAL | 12,006 | 58 km |
| 1995 | VISION | 11,931 | 75 km |
| 1985 | LEXINGTON | 11,550 | 83 km |
| 2015 | WRAGG | 8,455 | 66 km |
| 2009 | LOCKHEED | 8,287 | 91 km |
| 2003 | BIRD | 7,727 | 72 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 50°F (10°C) | 4.7 in | Wettest |
| February | 51°F (11°C) | 3.9 in | |
| March | 54°F (12°C) | 3.2 in | |
| April | 57°F (14°C) | 1.3 in | |
| May | 62°F (17°C) | 0.5 in | |
| June | 67°F (19°C) | 0.1 in | |
| July | 73°F (23°C) | 0.0 in | Warmest, Driest |
| August | 70°F (21°C) | 0.1 in | |
| September | 68°F (20°C) | 0.3 in | |
| October | 63°F (17°C) | 1.2 in | |
| November | 54°F (12°C) | 3.2 in | |
| December | 48°F (9°C) | 3.3 in | Coldest |
San Miguel CDP (Contra Costa County) has a seasonal temperature swing of 26°F / from 48°F in December to 73°F in July. Total annual precipitation is 21.8 inches, with January being the wettest month (4.7") and July the driest (0.0").