Weather & Climate in San Marcos, CA

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

San Marcos enjoys a temperate climate with an average annual temperature of 60°F (16°C). Winters average 51°F in January while summers reach 72°F in July. The area gets 325 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 29.4 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 636 feet.

Temperature

51°F Jan (10°C) 72°F Jul (22°C)

Annual Average	60.2°F
	11% above US avg
January Average	51°F (10°C)
July Average	72°F (22°C)
Sunny Days	325 days/yr

Geography

Elevation	636 ft (194 m)
Area	24.4 sq mi (63.2 km²)
Population Density	3,829/sq mi
Coordinates	33.1326°N, 117.1699°W
Timezone	America/Los_Angeles
County	Orange County County
Nearest Airport	San Diego International (SAN) 28 miles away

Precipitation & Snow

Annual Rainfall 29.4"

23% below US avg

Snowfall 1.0"

Wettest Month (Jan) 2.52"

Driest Month (Jul) 0.04"

Air Quality

AQI Median	48.0
Rating	Good

Natural Hazard Risk

Overall Risk	Very High
Risk Score	99.8 / 100
Social Vulnerability	24.9 / 100
Community Resilience	16.3 / 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

10,567 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M7.3.

Jun 28, 1992	The 1992 Landers, California Earthquake	M7.3	137 km	0 km
Jun 28, 1992	The 1992 Big Bear, California Earthquake	M6.3	123 km	4 km
Apr 23, 1992	The 1992 Joshua Tree, California Earthquake	M6.1	121 km	12 km
Jun 28, 1991	The 1991 Sierra Madre, California Earthquake	M5.8	148 km	8 km
Jun 28, 1992	3km NE of Yucca Valley, California	M5.8	132 km	-1 km
Jun 15, 2010	8km ESE of Ocotillo, CA	M5.7	127 km	9 km
Jun 28, 1992	2km SSW of Joshua Tree, California	M5.7	135 km	6 km
Jun 29, 1992	3km ESE of Yucca Valley, California	M5.7	129 km	10 km
Oct 16, 1999	7km ENE of Running Springs, CA	M5.6	124 km	6 km
Jun 28, 1992	11km SSE of Big Bear Lake, California	M5.5	118 km	10 km
Feb 28, 1990	The 1990 Upland, California Earthquake	M5.5	123 km	3 km
Jun 28, 1992	0km E of Yucca Valley, CA	M5.5	129 km	8 km
Jul 7, 2010	20km NNW of Borrego Springs, CA	M5.4	72 km	12 km
Jun 28, 1992	26km NNW of Yucca Valley, CA	M5.4	148 km	4 km
Jul 1, 1992	24km N of Yucca Valley, California	M5.3	148 km	5 km
Nov 27, 1992	10km NNW of Big Bear City, California	M5.3	137 km	0 km
Dec 4, 1992	10km SE of Lucerne Valley, California	M5.3	140 km	1 km
Sep 15, 1992	9km SE of Yucca Valley, California	M5.3	128 km	7 km
Jun 28, 1992	1km N of Big Bear Lake, California	M5.3	127 km	7 km
Jun 5, 2021	11km W of Calipatria, CA	M5.3	143 km	6 km

Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.

Tornado History

70 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2. Total: 9 injuries.

Date	Rating	Distance	Path	Fatalities
May 22, 2008	EF2	83 km	2.8 mi	0
Nov 7, 1966	EF2	90 km	0.2 mi	0
Feb 19, 2005	EF1	39 km	2.8 mi	0
Nov 10, 2000	EF1	25 km	0.4 mi	0
Jan 29, 1998	EF1	15 km	0.5 mi	0
Dec 21, 1997	EF1	98 km	1.0 mi	0
Nov 11, 1997	EF1	86 km	0.2 mi	0
Dec 22, 1996	EF1	95 km	0.1 mi	0
Mar 27, 1991	EF1	98 km	3.0 mi	0
Mar 27, 1991	EF1	2 km	0.2 mi	0
Mar 19, 1991	EF1	43 km	1.0 mi	0
Nov 9, 1982	EF1	68 km	0.2 mi	0
Feb 20, 1980	EF1	39 km	0.1 mi	0
Jan 31, 1979	EF1	95 km	2.0 mi	0
Dec 18, 1978	EF1	21 km	0.8 mi	0
Jul 20, 1974	EF1	72 km	1.0 mi	0
Nov 7, 1966	EF1	85 km	0.5 mi	0
Apr 8, 1965	EF1	89 km	0.1 mi	0
Oct 8, 1961	EF1	17 km	0.1 mi	0
Apr 1, 1958	EF1	71 km	0.5 mi	0

Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).

Tsunami History

2 tsunamis recorded within 500 km. Highest wave on record: 1.2 m (4 ft).

Year	Location	Cause	Max Wave	Deaths	Distance
1862	S. CALIFORNIA	Eruption + Earthquake	1.2 m	—	48 km
1855	S. CALIFORNIA	Eruption + Earthquake	—	—	138 km

Source: NOAA/NCEI Historical Tsunami Database.

Nearby Volcanoes

1 volcano within 200 km. Closest: Salton Buttes (145 km).

Name	Type	Elevation	Last Eruption	Distance
Salton Buttes	Lava dome(s)	-40 m (-131 ft)	210	145 km

Source: Smithsonian Institution Global Volcanism Program (GVP).

Wildfire History

20 wildfires (100+ acres) recorded within 100 km. Largest: CEDAR (268,362 acres, 2003).

Year	Name	Acres Burned	Distance
2003	CEDAR	268,362	43 km
2007	WITCH	167,551	38 km
2007	HARRIS	90,443	66 km
2002	PINES	65,407	56 km
2003	PARADISE	55,995	25 km
2007	POOMACHA	47,496	30 km
2006	ESPERANZA	40,566	85 km
2003	MINE/OTAY	37,232	64 km
2008	YELLOW	33,232	39 km
2022	FAIRVIEW	28,680	67 km
2013	MOUNTAIN	28,202	83 km
2007	SANTIAGO	27,605	80 km
1998	EDNA	27,561	86 km
2020	INDIA	24,193	38 km
1993	CALIFORNIA	23,899	58 km
2018	HOLY	22,845	69 km
1994	PALM	21,040	83 km
1993	ORTEGA	20,912	58 km
2013	SILVER	20,863	90 km
2003	COYOTE	19,215	62 km

Source: NIFC/IRWIN Wildfire Records (100+ acres).

Monthly Weather

Month	Avg Temperature	Precipitation	Summary
January	51°F (10°C)	2.5 in	Coldest, Wettest
February	57°F (14°C)	2.3 in
March	57°F (14°C)	2.3 in
April	60°F (16°C)	1.0 in
May	63°F (17°C)	0.3 in
June	66°F (19°C)	0.1 in
July	72°F (22°C)	0.0 in	Driest
August	72°F (22°C)	0.1 in	Warmest
September	70°F (21°C)	0.3 in
October	66°F (19°C)	0.4 in
November	60°F (16°C)	1.6 in
December	56°F (13°C)	1.8 in

San Marcos has a seasonal temperature swing of 21°F / from 51°F in January to 72°F in August. Total annual precipitation is 12.7 inches, with January being the wettest month (2.5") and July the driest (0.0").

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