Weather & Climate in Walnut Grove, CA

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

Walnut Grove enjoys a temperate climate with an average annual temperature of 62°F (17°C). Winters average 48°F in January while summers reach 77°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 24.8 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 -7 feet.

Temperature

48°F Jan (9°C) 77°F Jul (25°C)

Annual Average	62.1°F
	15% above US avg
January Average	48°F (9°C)
July Average	77°F (25°C)
Sunny Days	326 days/yr

Geography

Elevation	-7 ft (-2 m)
Area	10.2 sq mi (26.4 km²)
Population Density	95/sq mi
Coordinates	38.2506°N, 121.5350°W
Timezone	America/Los_Angeles
County	Sacramento County County
Nearest Airport	Sacramento International (SMF) 31 miles away

Precipitation & Snow

Annual Rainfall 24.8"

35% below US avg

Wettest Month (Jan) 3.62"

Driest Month (Jul) 0.04"

Air Quality

AQI Median	48.0
Rating	Good

Natural Hazard Risk

Overall Risk	Relatively High
Risk Score	98.1 / 100
Social Vulnerability	37.4 / 100
Community Resilience	57.0 / 100

Hazard Breakdown

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

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

Earthquake History

4,313 earthquakes (M2.5+) recorded within 150 km since 1990. Strongest on record: M6.0.

Aug 24, 2014	The 2014 South Napa, California Earthquake	M6.0	68 km	11 km
Apr 18, 1990	5 km NNW of Aromas, California	M5.4	147 km	5 km
Apr 18, 1990	4 km E of Interlaken, California	M5.1	144 km	7 km
Jan 16, 1993	9 km E of Gilroy, California	M4.9	137 km	7 km
Sep 3, 2000	5 km WSW of Yountville, California	M4.9	78 km	9 km
Apr 18, 1990	4 km NNW of Aromas, California	M4.9	147 km	6 km
May 14, 2002	5 km SSW of Gilroy, California	M4.9	143 km	7 km
Sep 4, 1995	13 km SW of Middletown, California	M4.8	116 km	7 km
May 12, 2006	7 km W of Cobb, California	M4.7	128 km	4 km
May 21, 1996	8 km ESE of East Foothills, California	M4.7	101 km	8 km
Apr 18, 1990	4 km N of Aromas, California	M4.7	147 km	4 km
Aug 11, 1993	14 km ESE of Alum Rock, California	M4.7	105 km	9 km
Jan 2, 2025	4 km NW of Cobb, CA	M4.7	125 km	1 km
Mar 24, 1991	1 km NNE of Interlaken, California	M4.6	144 km	15 km
Aug 18, 1999	0 km S of Bolinas, California	M4.6	108 km	8 km
Jan 11, 2000	6 km N of Geyserville, California	M4.6	133 km	6 km
Feb 18, 2004	4 km WNW of Cobb, California	M4.6	125 km	3 km
Sep 19, 2023	15 km SW of Westley, CA	M4.5	93 km	4 km
Jan 12, 2014	8 km W of Cobb, California	M4.5	128 km	2 km
Aug 3, 2006	5 km W of Glen Ellen, California	M4.5	93 km	9 km

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

Tornado History

78 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF2. Total: 2 injuries.

Date	Rating	Distance	Path	Fatalities
Feb 7, 1978	EF2	51 km	1.9 mi	0
Apr 27, 1953	EF2	82 km	0.1 mi	0
Mar 11, 2023	EF1	95 km	0.8 mi	0
Jan 10, 2023	EF1	70 km	0.4 mi	0
Dec 24, 2015	EF1	62 km	6.2 mi	0
Oct 22, 2012	EF1	96 km	4.0 mi	0
Oct 22, 2012	EF1	92 km	0.3 mi	0
Oct 22, 2012	EF1	91 km	2.0 mi	0
Jan 23, 2010	EF1	43 km	1.6 mi	0
Apr 14, 2006	EF1	82 km	0.5 mi	0
Dec 12, 1996	EF1	80 km	0.6 mi	0
Apr 19, 1988	EF1	35 km	0.2 mi	0
Apr 19, 1988	EF1	57 km	1.0 mi	0
Mar 22, 1983	EF1	55 km	2.0 mi	0
Jan 14, 1980	EF1	91 km	0.3 mi	0
Mar 4, 1978	EF1	93 km	2.5 mi	0
Mar 1, 1978	EF1	84 km	1.5 mi	0
May 31, 1967	EF1	37 km	0.1 mi	0
Jan 14, 2023	EF0	35 km	0.3 mi	0
Nov 8, 2022	EF0	21 km	0.8 mi	0

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

Tsunami History

5 tsunamis recorded within 500 km. Highest wave on record: 4.5 m (15 ft).

Year	Location	Cause	Max Wave	Deaths	Distance
1868	N. CALIFORNIA	Eruption + Earthquake	4.5 m	30	79 km
1989	N. CALIFORNIA	Earthquake	1.0 m	62	139 km
1856	N. CALIFORNIA	Eruption + Earthquake	0.6 m	—	107 km
1906	N. CALIFORNIA	Eruption + Earthquake	0.1 m	—	104 km
1865	N. CALIFORNIA	Eruption + Earthquake	—	—	121 km

Source: NOAA/NCEI Historical Tsunami Database.

Nearby Volcanoes

1 volcano within 200 km. Closest: Clear Lake (134 km).

Name	Type	Elevation	Last Eruption	Distance
Clear Lake	Volcanic field	1,439 m (4,721 ft)	Unknown	134 km

Source: Smithsonian Institution Global Volcanism Program (GVP).

Wildfire History

20 wildfires (100+ acres) recorded within 100 km. Largest: SCU LIGHTNING COMPLEX (405,787 acres, 2020).

Year	Name	Acres Burned	Distance
2020	SCU LIGHTNING COMPLEX	405,787	84 km
2020	HENNESSEY	314,241	77 km
2018	COUNTY	92,450	72 km
2015	BUTTE	72,894	82 km
2020	GLASS	68,020	94 km
2017	NUNS	56,883	85 km
2017	ATLAS	51,664	63 km
2004	RUMSEY	39,335	86 km
1999	SIXTEEN	37,162	92 km
1988	MILLER	35,750	53 km
1992	GULCH	18,019	93 km
2024	CORRAL	16,138	69 km
2006	ZAM ASSIST	14,404	65 km
2018	WAVERLY	12,238	66 km
2009	CORRAL	12,006	73 km
1996	SCOTT	8,828	55 km
2015	WRAGG	8,455	53 km
2003	BIRD	7,727	80 km
2014	MONTICELLO	6,984	57 km
1984	SITE 300 3	6,911	67 km

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

Monthly Weather

Month	Avg Temperature	Precipitation	Summary
January	48°F (9°C)	3.6 in	Wettest
February	51°F (10°C)	3.1 in
March	55°F (13°C)	2.5 in
April	59°F (15°C)	0.9 in
May	65°F (18°C)	0.4 in
June	70°F (21°C)	0.1 in
July	77°F (25°C)	0.0 in	Warmest, Driest
August	71°F (22°C)	0.1 in
September	69°F (21°C)	0.3 in
October	63°F (17°C)	0.9 in
November	53°F (12°C)	2.3 in
December	45°F (7°C)	2.4 in	Coldest

Walnut Grove has a seasonal temperature swing of 32°F / from 45°F in December to 77°F in July. Total annual precipitation is 16.6 inches, with January being the wettest month (3.6") and July the driest (0.0").

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