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Weather & Climate in Rossmoor, CA

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

Rossmoor enjoys a temperate climate with an average annual temperature of 65°F (18°C). Winters average 57°F in January while summers reach 73°F in July / relatively mild seasonal variation. 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 12.0 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 15 feet.

Temperature

57°F Jan (14°C) 73°F Jul (23°C)
Annual Average64.9°F
20% above US avg
January Average57°F (14°C)
July Average73°F (23°C)
Sunny Days330 days/yr

Geography

Elevation15 ft (5 m)
Area1.6 sq mi (4.0 km²)
Population Density7,625/sq mi
Coordinates33.7887°N, 118.0803°W
TimezoneAmerica/Los_Angeles
CountyOrange County County
Nearest AirportJohn Wayne/Orange County (SNA)
14 miles away

Precipitation & Snow

Annual Rainfall 12.0"
68% below US avg
Wettest Month (Jan) 2.91"
Driest Month (Jun) 0.08"

Air Quality

AQI Median48.0
RatingGood

Natural Hazard Risk

Overall RiskVery High
Risk Score99.8 / 100
Social Vulnerability24.9 / 100
Community Resilience16.3 / 100

Hazard Breakdown

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

Earthquake History

6,098 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M6.7.

Jan 17, 1994 Northridge, California, earthquake M6.7 63 km 18 km
Jun 28, 1992 The 1992 Big Bear, California Earthquake M6.3 124 km 4 km
Jan 17, 1994 1km ENE of Granada Hills, California M5.9 66 km 5 km
Jun 28, 1991 The 1991 Sierra Madre, California Earthquake M5.8 54 km 8 km
Oct 16, 1999 7km ENE of Running Springs, CA M5.6 108 km 6 km
Jan 17, 1994 7km NNE of Simi Valley, California M5.6 83 km 9 km
Jun 28, 1992 11km SSE of Big Bear Lake, California M5.5 121 km 10 km
Feb 28, 1990 The 1990 Upland, California Earthquake M5.5 53 km 3 km
Nov 27, 1992 10km NNW of Big Bear City, California M5.3 125 km 0 km
Jun 28, 1992 1km N of Big Bear Lake, California M5.3 120 km 7 km
Dec 4, 1992 10km SE of Lucerne Valley, California M5.3 127 km 1 km
Mar 20, 1994 3km WNW of Panorama City, California M5.2 61 km 12 km
Jan 18, 1994 10km ESE of Piru, California M5.2 87 km 11 km
Aug 17, 1992 7km SE of Big Bear Lake, California M5.2 121 km 9 km
Jun 12, 2005 10km ESE of Anza, CA M5.2 143 km 13 km
Jan 17, 1994 9km N of Chatsworth, California M5.2 79 km 5 km
Mar 29, 2014 2km NW of Brea, CA M5.1 22 km 5 km
Aug 20, 2023 7 km SE of Ojai, CA M5.1 123 km 5 km
Jan 19, 1994 10km SSW of Valencia, California M5.1 82 km 11 km
Apr 26, 1997 12km ESE of Piru, California M5.1 84 km 16 km
Source: USGS Earthquake Catalog (M2.5+, 1990-2025). Sorted by magnitude.

Tornado History

106 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2. Total: 57 injuries.

Date Rating Distance Path Fatalities
May 22, 2008 EF2 77 km 2.8 mi 0
Mar 1, 1983 EF2 34 km 3.5 mi 0
Nov 9, 1982 EF2 55 km 1.0 mi 0
Nov 9, 1982 EF2 11 km 10.0 mi 0
Nov 7, 1966 EF2 24 km 10.3 mi 0
Nov 7, 1966 EF2 24 km 0.1 mi 0
Nov 7, 1966 EF2 21 km 0.2 mi 0
Mar 22, 2023 EF1 24 km 0.5 mi 0
Jan 19, 2010 EF1 9 km 4.6 mi 0
Feb 19, 2005 EF1 91 km 2.8 mi 0
Jan 9, 1998 EF1 8 km 1.5 mi 0
Dec 21, 1997 EF1 15 km 1.0 mi 0
Nov 11, 1997 EF1 27 km 0.2 mi 0
Jan 14, 1993 EF1 16 km 1.0 mi 0
Dec 7, 1992 EF1 9 km 0.1 mi 0
Dec 7, 1992 EF1 16 km 0.1 mi 0
Mar 20, 1992 EF1 36 km 0.2 mi 0
Mar 27, 1991 EF1 15 km 3.0 mi 0
Mar 16, 1986 EF1 16 km 1.2 mi 0
Oct 1, 1983 EF1 29 km 0.3 mi 0
Source: NOAA Storm Prediction Center (EF0+, 1950-2024, US only).

Tsunami History

4 tsunamis recorded within 500 km. Highest wave on record: 3.1 m (10 ft).

Year Location Cause Max Wave Deaths Distance
1930 S. CALIFORNIA Eruption + Earthquake 3.1 m 1 58 km
1862 S. CALIFORNIA Eruption + Earthquake 1.2 m - 146 km
1994 WEST COAST, USA Earthquake 0.1 m 57 63 km
1855 S. CALIFORNIA Eruption + Earthquake - - 35 km
Source: NOAA/NCEI Historical Tsunami Database.

Wildfire History

20 wildfires (100+ acres) recorded within 100 km. Largest: STATION (165,368 acres, 2009).

Year Name Acres Burned Distance
2009 STATION 165,368 60 km
2020 BOBCAT 115,728 61 km
2003 SIMI 107,756 89 km
2018 WOOLSEY 97,962 78 km
2003 OLD 90,180 89 km
2003 GRAND PRIX 50,799 71 km
2016 SAND 41,561 71 km
2007 BUCKWEED 41,332 88 km
1993 GREEN MEADOWS 38,115 90 km
2002 WILLIAMS 37,505 53 km
2016 BLUE CUT 36,856 80 km
2008 YELLOW 33,232 73 km
2008 FREEWAY COMPLEX 29,350 34 km
2007 SANTIAGO 27,605 40 km
2020 INDIA 24,193 74 km
2005 TOPANGA 24,133 74 km
2013 SPRINGS 24,042 93 km
1993 CALIFORNIA 23,899 99 km
2018 HOLY 22,845 57 km
1993 ORTEGA 20,912 59 km
Source: NIFC/IRWIN Wildfire Records (100+ acres).

Monthly Weather

Month Avg Temperature Precipitation Summary
January 57°F (14°C) 2.9 in Wettest
February 58°F (15°C) 2.9 in
March 59°F (15°C) 2.4 in
April 62°F (17°C) 0.6 in
May 65°F (18°C) 0.2 in
June 68°F (20°C) 0.1 in
July 73°F (23°C) 0.0 in Warmest, Driest
August 73°F (23°C) 0.1 in
September 72°F (22°C) 0.3 in
October 67°F (20°C) 0.4 in
November 61°F (16°C) 1.3 in
December 57°F (14°C) 1.9 in Coldest

Rossmoor has a seasonal temperature swing of 17°F / from 57°F in December to 73°F in July. Total annual precipitation is 13.1 inches, with January being the wettest month (2.9") and July the driest (0.0").

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