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Weather & Climate in Rancho Cucamonga, CA

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

Rancho Cucamonga enjoys a temperate climate with an average annual temperature of 63°F (17°C). Winters average 50°F in January while summers reach 82°F in July. The area gets 328 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 48.5 inches (wetter than the 38-inch national average). The area receives 13.6 inches of snow annually. Air quality is rated Good with a median AQI of 48. The city sits at an elevation of 1,427 feet.

Temperature

50°F Jan (10°C) 82°F Jul (28°C)
Annual Average63.0°F
17% above US avg
January Average50°F (10°C)
July Average82°F (28°C)
Sunny Days328 days/yr

Geography

Elevation1,427 ft (435 m)
Area40.0 sq mi (103.6 km²)
Population Density3,756/sq mi
Coordinates34.1303°N, 117.5661°W
TimezoneAmerica/Los_Angeles
CountyOrange County County
Nearest AirportOntario International (ONT)
6 miles away

Precipitation & Snow

Annual Rainfall 48.5"
28% above US avg
Snowfall 13.6"
Wettest Month (Feb) 3.11"
Driest Month (Jun) 0.04"

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

13,513 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M7.3.

Jun 28, 1992 The 1992 Landers, California Earthquake M7.3 104 km 0 km
Oct 16, 1999 The 1999 Hector Mine, California Earthquake M7.1 131 km 14 km
Jan 17, 1994 Northridge, California, earthquake M6.7 90 km 18 km
Jun 28, 1992 The 1992 Big Bear, California Earthquake M6.3 69 km 4 km
Apr 23, 1992 The 1992 Joshua Tree, California Earthquake M6.1 117 km 12 km
Jan 17, 1994 1km ENE of Granada Hills, California M5.9 87 km 5 km
Jun 28, 1991 The 1991 Sierra Madre, California Earthquake M5.8 42 km 8 km
Oct 16, 1999 13km WSW of Ludlow, CA M5.8 132 km 14 km
Jun 28, 1992 3km NE of Yucca Valley, California M5.8 107 km -1 km
Jun 28, 1992 2km SSW of Joshua Tree, California M5.7 114 km 6 km
Jun 29, 1992 3km ESE of Yucca Valley, California M5.7 107 km 10 km
Jul 11, 1992 12km NW of California City, California M5.7 129 km 10 km
Oct 16, 1999 7km ENE of Running Springs, CA M5.6 50 km 6 km
Jan 17, 1994 7km NNE of Simi Valley, California M5.6 106 km 9 km
Jun 28, 1992 11km SSE of Big Bear Lake, California M5.5 66 km 10 km
Feb 28, 1990 The 1990 Upland, California Earthquake M5.5 12 km 3 km
Jun 28, 1992 0km E of Yucca Valley, CA M5.5 105 km 8 km
Jul 7, 2010 20km NNW of Borrego Springs, CA M5.4 128 km 12 km
Jul 5, 1992 21km SW of Ludlow, California M5.4 125 km 5 km
Jun 28, 1992 26km NNW of Yucca Valley, CA M5.4 100 km 4 km
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.

Tornado History

122 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2. Total: 55 injuries.

Date Rating Distance Path Fatalities
May 22, 2008 EF2 40 km 2.8 mi 0
Mar 1, 1983 EF2 76 km 3.5 mi 0
Nov 9, 1982 EF2 82 km 1.0 mi 0
Nov 9, 1982 EF2 70 km 10.0 mi 0
Nov 7, 1966 EF2 77 km 10.3 mi 0
Nov 7, 1966 EF2 72 km 0.1 mi 0
Nov 7, 1966 EF2 63 km 0.2 mi 0
Jun 25, 1954 EF2 65 km 0.1 mi 0
Mar 22, 2023 EF1 54 km 0.5 mi 0
Jan 19, 2010 EF1 69 km 4.6 mi 0
Aug 4, 2008 EF1 93 km 1.1 mi 0
Feb 19, 2005 EF1 81 km 2.8 mi 0
Jan 9, 1998 EF1 68 km 1.5 mi 0
Dec 21, 1997 EF1 65 km 1.0 mi 0
Nov 11, 1997 EF1 55 km 0.2 mi 0
May 18, 1997 EF1 63 km 9.0 mi 0
May 18, 1997 EF1 64 km 3.5 mi 0
May 11, 1997 EF1 55 km 0.2 mi 0
Dec 22, 1996 EF1 76 km 0.1 mi 0
Jan 14, 1993 EF1 45 km 1.0 mi 0
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).

Tsunami History

3 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 1 100 km
1994 WEST COAST, USA Earthquake 0.1 m 57 90 km
1855 S. CALIFORNIA Eruption + Earthquake — — 49 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 57 km
2020 BOBCAT 115,728 40 km
2003 OLD 90,180 29 km
2006 MILLARD 86,585 87 km
1999 WILLOW 63,525 49 km
2003 GRAND PRIX 50,799 11 km
2016 SAND 41,561 78 km
2007 BUCKWEED 41,332 91 km
2006 ESPERANZA 40,566 70 km
2002 WILLIAMS 37,505 21 km
2016 BLUE CUT 36,856 22 km
2008 YELLOW 33,232 83 km
2020 APPLE 32,374 65 km
2015 LAKE 30,421 74 km
2008 FREEWAY COMPLEX 29,350 29 km
2022 FAIRVIEW 28,680 82 km
2013 MOUNTAIN 28,202 97 km
2007 SANTIAGO 27,605 46 km
1998 EDNA 27,561 59 km
2020 INDIA 24,193 82 km
Source: NIFC/IRWIN Wildfire Records (100+ acres).

Monthly Weather

Month Avg Temperature Precipitation Summary
January 50°F (10°C) 3.0 in Coldest
February 56°F (13°C) 3.1 in Wettest
March 57°F (14°C) 2.7 in
April 61°F (16°C) 1.0 in
May 65°F (19°C) 0.3 in
June 71°F (22°C) 0.0 in Driest
July 82°F (28°C) 0.0 in Warmest
August 77°F (25°C) 0.2 in
September 74°F (23°C) 0.4 in
October 67°F (20°C) 0.4 in
November 59°F (15°C) 1.6 in
December 54°F (12°C) 2.0 in

Rancho Cucamonga has a seasonal temperature swing of 32°F / from 50°F in January to 82°F in July. Total annual precipitation is 14.7 inches, with February being the wettest month (3.1") and June the driest (0.0").

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