Weather & Climate in Altadena, CA

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

Altadena enjoys a temperate climate with an average annual temperature of 66°F (19°C). Winters average 57°F in January while summers reach 76°F in July / relatively mild seasonal variation. The area gets 326 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 20.1 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 1,414 feet.

Temperature

57°F Jan (14°C) 76°F Jul (24°C)

Annual Average	66.0°F
	22% above US avg
January Average	57°F (14°C)
July Average	76°F (24°C)
Sunny Days	326 days/yr

Geography

Elevation	1,414 ft (431 m)
Area	8.7 sq mi (22.6 km²)
Population Density	4,949/sq mi
Coordinates	34.1922°N, 118.1356°W
Timezone	America/Los_Angeles
County	Los Angeles County County
Nearest Airport	Bob Hope (BUR) 13 miles away

Precipitation & Snow

Annual Rainfall 20.1"

47% below US avg

Snowfall 0.0"

Wettest Month (Feb) 4.13"

Driest Month (Jun) 0.08"

Air Quality

AQI Median	48.0
Rating	Good

Natural Hazard Risk

Overall Risk	Very High
Risk Score	100.0 / 100
Social Vulnerability	55.4 / 100
Community Resilience	13.6 / 100

Hazard Breakdown

Tornado	Relatively High
Hurricane	No Rating
Earthquake	Very High
Wildfire	Very High
Flood	Very High
Hail	Relatively Moderate
Strong Wind	Relatively Moderate
Heat Wave	Relatively High
Winter Weather	Relatively Moderate
Lightning	Very High
Drought	Relatively Low
Cold Wave	Very Low
Landslide	Relatively High
Coastal Flood	Relatively High
Tsunami	Relatively Low
Avalanche	Relatively High

Source: FEMA National Risk Index v1.20 (Dec 2025)

Earthquake History

7,811 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M6.7.

Jan 17, 1994	Northridge, California, earthquake	M6.7	37 km	18 km
Jun 28, 1992	The 1992 Big Bear, California Earthquake	M6.3	120 km	4 km
Jan 17, 1994	1km ENE of Granada Hills, California	M5.9	34 km	5 km
Jun 28, 1991	The 1991 Sierra Madre, California Earthquake	M5.8	16 km	8 km
Jul 11, 1992	12km NW of California City, California	M5.7	113 km	10 km
Oct 16, 1999	7km ENE of Running Springs, CA	M5.6	101 km	6 km
Jan 17, 1994	7km NNE of Simi Valley, California	M5.6	54 km	9 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	41 km	3 km
Nov 27, 1992	10km NNW of Big Bear City, California	M5.3	115 km	0 km
Mar 18, 1997	20km ENE of Barstow, California	M5.3	148 km	1 km
Jun 28, 1992	1km N of Big Bear Lake, California	M5.3	113 km	7 km
Dec 4, 1992	10km SE of Lucerne Valley, California	M5.3	115 km	1 km
Jan 18, 1994	10km ESE of Piru, California	M5.2	56 km	11 km
Mar 20, 1994	3km WNW of Panorama City, California	M5.2	32 km	12 km
Aug 17, 1992	7km SE of Big Bear Lake, California	M5.2	117 km	9 km
Aug 7, 2024	24 km SW of Lamont, CA	M5.2	135 km	12 km
Jan 17, 1994	9km N of Chatsworth, California	M5.2	47 km	5 km
May 28, 1993	21km SW of Lamont, California	M5.2	138 km	21 km
Mar 29, 2014	2km NW of Brea, CA	M5.1	35 km	5 km

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

Tornado History

114 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2. Total: 54 injuries.

Date	Rating	Distance	Path	Fatalities
May 22, 2008	EF2	89 km	2.8 mi	0
Mar 1, 1983	EF2	32 km	3.5 mi	0
Nov 9, 1982	EF2	29 km	1.0 mi	0
Nov 9, 1982	EF2	46 km	10.0 mi	0
Nov 7, 1966	EF2	42 km	10.3 mi	0
Nov 7, 1966	EF2	64 km	0.2 mi	0
Nov 7, 1966	EF2	36 km	0.1 mi	0
Jun 25, 1954	EF2	99 km	0.1 mi	0
Mar 22, 2023	EF1	22 km	0.5 mi	0
Jan 19, 2010	EF1	53 km	4.6 mi	0
Jan 9, 1998	EF1	46 km	1.5 mi	0
Dec 21, 1997	EF1	59 km	1.0 mi	0
Nov 11, 1997	EF1	64 km	0.2 mi	0
May 18, 1997	EF1	99 km	9.0 mi	0
May 18, 1997	EF1	96 km	3.5 mi	0
May 11, 1997	EF1	93 km	0.2 mi	0
Jan 14, 1993	EF1	39 km	1.0 mi	0
Dec 7, 1992	EF1	45 km	0.1 mi	0
Dec 7, 1992	EF1	51 km	0.1 mi	0
Mar 20, 1992	EF1	11 km	0.2 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	50 km
1994	WEST COAST, USA	Earthquake	0.1 m	57	37 km
1855	S. CALIFORNIA	Eruption + Earthquake	—	—	11 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	15 km
2006	DAY	159,713	90 km
2020	BOBCAT	115,728	24 km
2003	SIMI	107,756	62 km
2018	WOOLSEY	97,962	64 km
2003	OLD	90,180	79 km
2003	PIRU	63,920	74 km
1999	WILLOW	63,525	96 km
2003	GRAND PRIX	50,799	61 km
1985	FERNDALE	46,724	96 km
2016	SAND	41,561	30 km
2007	BUCKWEED	41,332	46 km
1993	GREEN MEADOWS	38,115	78 km
2002	WILLIAMS	37,505	33 km
2007	RANCH	37,009	65 km
2016	BLUE CUT	36,856	60 km
2013	POWERHOUSE	32,329	61 km
2020	LAKE	30,971	67 km
2008	FREEWAY COMPLEX	29,350	47 km
2007	SANTIAGO	27,605	68 km

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

Monthly Weather

Month	Avg Temperature	Precipitation	Summary
January	57°F (14°C)	3.9 in
February	48°F (9°C)	4.1 in	Wettest
March	50°F (10°C)	3.5 in
April	54°F (12°C)	1.6 in
May	59°F (15°C)	0.4 in
June	66°F (19°C)	0.1 in	Driest
July	76°F (24°C)	0.1 in	Warmest
August	74°F (23°C)	0.2 in
September	70°F (21°C)	0.5 in
October	62°F (17°C)	0.5 in
November	53°F (12°C)	2.6 in
December	48°F (9°C)	3.0 in	Coldest

Altadena has a seasonal temperature swing of 28°F / from 48°F in December to 76°F in July. Total annual precipitation is 20.5 inches, with February being the wettest month (4.1") and June the driest (0.1").

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