Weather & Climate in Portola, CA

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

Portola experiences four distinct seasons with an average annual temperature of 47°F (8°C). Winters average 31°F in January while summers reach 66°F in July. 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 23.3 inches (drier than the 38-inch national average). The area receives 37.8 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 48. The city sits at an elevation of 4,975 feet.

Temperature

31°F Jan (-0°C) 66°F Jul (19°C)

Annual Average	46.7°F
	14% below US avg
January Average	31°F (-0°C)
July Average	66°F (19°C)
Sunny Days	326 days/yr

Geography

Elevation	4,975 ft (1,516 m)
Area	5.4 sq mi (14.0 km²)
Population Density	455/sq mi
Coordinates	39.8208°N, 120.4743°W
Timezone	America/Los_Angeles
County	Sierra County County
Nearest Airport	Reno/Tahoe International (RNO) 44 miles away

Precipitation & Snow

Annual Rainfall 23.3"

39% below US avg

Snowfall 37.8"

Wettest Month (Jan) 4.41"

Driest Month (Jul) 0.31"

Air Quality

AQI Median	48.0
Rating	Good

Natural Hazard Risk

Overall Risk	Very Low
Risk Score	31.5 / 100
Social Vulnerability	63.2 / 100
Community Resilience	31.4 / 100

Hazard Breakdown

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

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

Earthquake History

2,396 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M6.1.

Sep 12, 1994	4 km S of Carter Springs, Nevada	M6.1	132 km	14 km
May 24, 2013	2 km NNE of Canyondam, California	M5.7	65 km	8 km
May 11, 2023	Lake Almanor Earthquake	M5.5	69 km	6 km
Aug 10, 2001	3 km N of Blairsden, California	M5.2	12 km	5 km
May 12, 2023	4km NW of Canyondam, CA	M5.2	68 km	6 km
Sep 12, 1994	8 km ESE of Mesa Vista, California	M5.1	134 km	-1 km
Apr 26, 2008	1 km NW of Mogul, Nevada	M5.1	57 km	3 km
May 24, 2013	1km NNW of Canyondam, CA	M4.9	65 km	4 km
Dec 22, 1995	California-Nevada border region	M4.9	142 km	4 km
Apr 26, 2008	0 km N of Mogul, Nevada	M4.8	57 km	3 km
Oct 30, 1998	4 km N of Tahoe Vista, California	M4.8	70 km	1 km
Dec 28, 1995	9 km WNW of Topaz Lake, Nevada	M4.8	142 km	-1 km
Feb 10, 1993	28 km SW of Empire, Nevada	M4.8	100 km	5 km
Jun 26, 2005	8 km NNW of Tahoe Vista, California	M4.8	66 km	-2 km
Dec 23, 1995	8 km WNW of Topaz Lake, Nevada	M4.7	141 km	-1 km
May 7, 2021	19km NW of Truckee, CA	M4.7	42 km	10 km
Mar 21, 2020	5 km NE of Indian Hills, Nevada	M4.5	101 km	8 km
Sep 20, 1994	9 km WNW of Topaz Lake, Nevada	M4.5	140 km	-1 km
Nov 15, 1995	9 km SW of Cold Springs, Nevada	M4.5	42 km	-1 km
Aug 4, 2016	5 km WNW of Patton Village, California	M4.5	43 km	7 km

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

Tornado History

22 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2. Total: 7 injuries.

Date	Rating	Distance	Path	Fatalities
Feb 10, 1994	EF2	100 km	0.3 mi	0
Aug 15, 2020	EF1	31 km	0.1 mi	0
Aug 14, 2020	EF1	31 km	0.4 mi	0
Dec 17, 1992	EF1	96 km	5.0 mi	0
Dec 17, 1992	EF1	100 km	1.0 mi	0
Mar 23, 1978	EF1	98 km	0.1 mi	0
Nov 3, 1973	EF1	78 km	25.9 mi	0
Jul 16, 1973	EF1	65 km	1.0 mi	0
Nov 18, 2020	EF0	95 km	0.5 mi	0
Sep 21, 2017	EF0	97 km	0.4 mi	0
Sep 13, 2017	EF0	84 km	2.0 mi	0
Jul 20, 2015	EF0	42 km	3.2 mi	0
Apr 27, 2005	EF0	93 km	0.2 mi	0
Jul 24, 2004	EF0	60 km	0.1 mi	0
Aug 2, 2003	EF0	53 km	0.1 mi	0
Aug 2, 2003	EF0	80 km	0.1 mi	0
Aug 1, 2002	EF0	71 km	0.1 mi	0
Feb 10, 2000	EF0	67 km	0.5 mi	0
Jul 13, 1999	EF0	67 km	0.1 mi	0
Jul 30, 1998	EF0	56 km	2.0 mi	0

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

Nearby Volcanoes

2 volcanoes within 200 km. Closest: Lassen Volcanic Center (115 km).

Name	Type	Elevation	Last Eruption	Distance
Lassen Volcanic Center	Stratovolcano	3,187 m (10,456 ft)	1917	115 km
Soda Lakes	Maar(s)	1,251 m (4,104 ft)	Unknown	141 km

Source: Smithsonian Institution Global Volcanism Program (GVP).

Wildfire History

20 wildfires (100+ acres) recorded within 100 km. Largest: DIXIE (979,795 acres, 2021).

Year	Name	Acres Burned	Distance
2021	DIXIE	979,795	65 km
2020	NORTH COMPLEX	316,556	57 km
2012	RUSH	306,811	93 km
2018	CAMP	153,687	94 km
2021	SUGAR	108,368	29 km
2014	KING	99,070	99 km
2017	LONG VALLEY	80,456	51 km
2012	CHIPS	79,978	69 km
2022	MOSQUITO	77,858	89 km
2007	MOONLIGHT	65,718	50 km
2019	WALKER	58,747	31 km
2018	PERRY	53,734	84 km
2008	BTU LIGHTNING COMPLEX (LONG BRANCH-JACK)	52,091	83 km
2000	STORRIE	49,588	73 km
1994	COTTONWOOD	47,912	34 km
1999	FISH COMPLEX (FISH SPRINGS)	47,030	59 km
2020	LOYALTON	45,484	33 km
1987	CLARK	39,194	35 km
1988	49R	36,673	90 km
2016	TULE	35,341	72 km

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

Monthly Weather

Month	Avg Temperature	Precipitation	Summary
January	31°F (-0°C)	4.4 in	Coldest, Wettest
February	34°F (1°C)	3.7 in
March	38°F (3°C)	3.3 in
April	43°F (6°C)	1.4 in
May	50°F (10°C)	1.2 in
June	58°F (14°C)	0.8 in
July	66°F (19°C)	0.3 in	Warmest, Driest
August	66°F (19°C)	0.4 in
September	59°F (15°C)	0.8 in
October	51°F (11°C)	1.9 in
November	40°F (4°C)	3.9 in
December	32°F (0°C)	3.8 in

Portola has a seasonal temperature swing of 34°F / from 31°F in January to 66°F in July. Total annual precipitation is 25.9 inches, with January being the wettest month (4.4") and July the driest (0.3").

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