Weather & Climate in Knightsen, CA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Knightsen enjoys a temperate climate with an average annual temperature of 63°F (17°C). Winters average 48°F in January while summers reach 76°F in July. Annual precipitation totals 12.6 inches (drier than the 38-inch national average). Air quality is rated Good with a median AQI of 48. 54% of days have good air quality. The city sits at an elevation of 20 feet.
Temperature
48°F Jan (9°C)
76°F Jul (24°C)
| Annual Average | 62.5°F |
| 16% above US avg | |
| January Average | 48°F (9°C) |
| July Average | 76°F (24°C) |
Geography
| Elevation | 20 ft (6 m) |
| Area | 8.5 sq mi (21.9 km²) |
| Population Density | 241/sq mi |
| Coordinates | 37.9624°N, 121.6486°W |
| Timezone | America/Los_Angeles |
| County | Contra Costa County County |
| Nearest Airport | Metro Oakland International (OAK) 35 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 48.0 |
| Rating | Good |
| Good Days % | 53.7% |
| Unhealthy Days | 0 |
Natural Hazard Risk
| Overall Risk | Very High |
| Risk Score | 99.5 / 100 |
| Social Vulnerability | 21.5 / 100 |
| Community Resilience | 67.8 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Earthquake | Relatively High |
| Wildfire | Relatively Moderate |
| Flood | Very High |
| Hail | Very Low |
| Strong Wind | Relatively Low |
| Heat Wave | Relatively High |
| Winter Weather | Very Low |
| Lightning | Relatively High |
| Drought | Relatively High |
| Cold Wave | No Rating |
| Landslide | Relatively High |
| Coastal Flood | Relatively Moderate |
| Tsunami | Relatively Low |
| Volcano | Very Low |
| Avalanche | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
5,540 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 | 65 km | 11 km |
| Apr 18, 1990 | 5 km NNW of Aromas, California | M5.4 | 115 km | 5 km |
| Aug 12, 1998 | 10 km SW of Ridgemark, California | M5.1 | 135 km | 9 km |
| Apr 18, 1990 | 4 km E of Interlaken, California | M5.1 | 112 km | 7 km |
| Jan 16, 1993 | 9 km E of Gilroy, California | M4.9 | 106 km | 7 km |
| May 14, 2002 | 5 km SSW of Gilroy, California | M4.9 | 111 km | 7 km |
| Sep 3, 2000 | 5 km WSW of Yountville, California | M4.9 | 81 km | 9 km |
| Apr 18, 1990 | 4 km NNW of Aromas, California | M4.9 | 115 km | 6 km |
| Apr 19, 1996 | 2 km E of Aromas, California | M4.9 | 120 km | 5 km |
| Sep 4, 1995 | 13 km SW of Middletown, California | M4.8 | 125 km | 7 km |
| May 12, 2006 | 7 km W of Cobb, California | M4.7 | 139 km | 4 km |
| May 21, 1996 | 8 km ESE of East Foothills, California | M4.7 | 67 km | 8 km |
| Apr 18, 1990 | 4 km N of Aromas, California | M4.7 | 115 km | 4 km |
| Aug 11, 1993 | 14 km ESE of Alum Rock, California | M4.7 | 72 km | 9 km |
| Jan 2, 2025 | 4 km NW of Cobb, CA | M4.7 | 138 km | 1 km |
| Aug 18, 1999 | 0 km S of Bolinas, California | M4.6 | 91 km | 8 km |
| Mar 24, 1991 | 1 km NNE of Interlaken, California | M4.6 | 111 km | 15 km |
| Jan 11, 2000 | 6 km N of Geyserville, California | M4.6 | 142 km | 6 km |
| Feb 18, 2004 | 4 km WNW of Cobb, California | M4.6 | 138 km | 3 km |
| Jan 12, 2014 | 8 km W of Cobb, California | M4.5 | 139 km | 2 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 | 74 km | 0.6 mi | 0 |
| Feb 7, 1978 | EF2 | 84 km | 1.9 mi | 0 |
| Apr 27, 1953 | EF2 | 67 km | 0.1 mi | 0 |
| Jan 11, 1951 | EF2 | 78 km | 5.7 mi | 0 |
| Mar 11, 2023 | EF1 | 98 km | 0.8 mi | 0 |
| Jan 10, 2023 | EF1 | 79 km | 0.4 mi | 0 |
| Dec 24, 2015 | EF1 | 95 km | 6.2 mi | 0 |
| Nov 15, 2015 | EF1 | 88 km | 3.0 mi | 0 |
| Jan 23, 2010 | EF1 | 12 km | 1.6 mi | 0 |
| Apr 14, 2006 | EF1 | 67 km | 0.5 mi | 0 |
| Mar 20, 2005 | EF1 | 76 km | 3.0 mi | 0 |
| May 5, 1998 | EF1 | 77 km | 0.3 mi | 0 |
| Dec 12, 1996 | EF1 | 73 km | 0.6 mi | 0 |
| Apr 19, 1988 | EF1 | 49 km | 0.2 mi | 0 |
| Apr 19, 1988 | EF1 | 90 km | 1.0 mi | 0 |
| Mar 22, 1983 | EF1 | 88 km | 2.0 mi | 0 |
| Jan 14, 1980 | EF1 | 57 km | 0.3 mi | 0 |
| Mar 4, 1978 | EF1 | 93 km | 1.0 mi | 0 |
| Mar 4, 1978 | EF1 | 81 km | 2.5 mi | 0 |
| Mar 1, 1978 | EF1 | 71 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 | 49 km |
| 1989 | N. CALIFORNIA | Earthquake | 1.0 m | 62 | 105 km |
| 1856 | N. CALIFORNIA | Eruption + Earthquake | 0.6 m | - | 77 km |
| 1906 | N. CALIFORNIA | Eruption + Earthquake | 0.1 m | - | 80 km |
| 1865 | N. CALIFORNIA | Eruption + Earthquake | - | - | 88 km |
Source: NOAA/NCEI Historical Tsunami Database.
Nearby Volcanoes
1 volcano within 200 km. Closest: Clear Lake (149 km).
| Name | Type | Elevation | Last Eruption | Distance |
| Clear Lake | Volcanic field | 1,439 m (4,721 ft) | Unknown | 149 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 | 54 km |
| 2020 | HENNESSEY | 314,241 | 92 km |
| 2018 | COUNTY | 92,450 | 92 km |
| 2015 | BUTTE | 72,894 | 98 km |
| 2017 | NUNS | 56,883 | 86 km |
| 2017 | ATLAS | 51,664 | 68 km |
| 2007 | LICK | 47,424 | 85 km |
| 2006 | CANYON | 36,851 | 72 km |
| 1988 | MILLER | 35,750 | 65 km |
| 2003 | ANNIE | 17,383 | 89 km |
| 2024 | CORRAL | 16,138 | 40 km |
| 2006 | ZAM ASSIST | 14,404 | 91 km |
| 2018 | WAVERLY | 12,238 | 71 km |
| 2009 | CORRAL | 12,006 | 43 km |
| 1985 | LEXINGTON | 11,550 | 94 km |
| 1996 | SCOTT | 8,828 | 85 km |
| 2015 | WRAGG | 8,455 | 68 km |
| 2003 | BIRD | 7,727 | 53 km |
| 2014 | MONTICELLO | 6,984 | 74 km |
| 1984 | SITE 300 3 | 6,911 | 38 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 48°F (9°C) | 2.7 in | Coldest, Wettest |
| February | 52°F (11°C) | 2.4 in | |
| March | 57°F (14°C) | 2.0 in | |
| April | 61°F (16°C) | 0.9 in | |
| May | 67°F (19°C) | 0.4 in | |
| June | 73°F (23°C) | 0.1 in | |
| July | 76°F (24°C) | 0.0 in | Warmest, Driest |
| August | 75°F (24°C) | 0.0 in | |
| September | 73°F (23°C) | 0.1 in | |
| October | 66°F (19°C) | 0.4 in | |
| November | 55°F (13°C) | 1.2 in | |
| December | 48°F (9°C) | 2.5 in |
Knightsen has a seasonal temperature swing of 28°F / from 48°F in January to 76°F in July. Total annual precipitation is 12.6 inches, with January being the wettest month (2.7") and July the driest (0.0").