Temperature, precipitation, air quality, natural hazards, and monthly weather data.
August enjoys a temperate climate with an average annual temperature of 64°F (18°C). Winters average 49°F in January while summers reach 78°F in July. The area gets 330 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 17.3 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 23 feet.
Temperature
49°F Jan (9°C)78°F Jul (25°C)
Annual Average
63.9°F
18% above US avg
January Average
49°F (9°C)
July Average
78°F (25°C)
Sunny Days
330 days/yr
Geography
Elevation
23 ft (7 m)
Area
1.3 sq mi (3.2 km²)
Population Density
6,723/sq mi
Coordinates
37.9796°N, 121.2625°W
Timezone
America/Los_Angeles
County
San Joaquin County County
Nearest Airport
Sacramento International (SMF) 53 miles away
Precipitation & Snow
Annual Rainfall17.3"
55% below US avg
Snowfall0.0"
Wettest Month (Jan)2.72"
Driest Month (Jul)0.04"
Air Quality
AQI Median
48.0
Rating
Good
Natural Hazard Risk
Overall Risk
Relatively High
Risk Score
98.6 / 100
Social Vulnerability
39.7 / 100
Community Resilience
47.0 / 100
Hazard Breakdown
Tornado
Relatively Low
Earthquake
Relatively High
Wildfire
Relatively Moderate
Flood
Relatively High
Hail
Relatively Low
Strong Wind
Relatively Low
Heat Wave
Relatively High
Winter Weather
Relatively Low
Lightning
Relatively High
Drought
Very High
Cold Wave
No Rating
Landslide
Very Low
Volcano
Very Low
Avalanche
Very Low
Source: FEMA National Risk Index v1.20 (Dec 2025)
Earthquake History
3,547 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
96 km
11 km
Apr 18, 1990
5 km NNW of Aromas, California
M5.4
122 km
5 km
Apr 18, 1990
4 km E of Interlaken, California
M5.1
120 km
7 km
Aug 12, 1998
10 km SW of Ridgemark, California
M5.1
137 km
9 km
Jan 16, 1993
9 km E of Gilroy, California
M4.9
108 km
7 km
May 14, 2002
5 km SSW of Gilroy, California
M4.9
117 km
7 km
Sep 3, 2000
5 km WSW of Yountville, California
M4.9
110 km
9 km
Apr 19, 1996
2 km E of Aromas, California
M4.9
126 km
5 km
Apr 18, 1990
4 km NNW of Aromas, California
M4.9
122 km
6 km
May 21, 1996
8 km ESE of East Foothills, California
M4.7
80 km
8 km
Apr 18, 1990
4 km N of Aromas, California
M4.7
122 km
4 km
Aug 11, 1993
14 km ESE of Alum Rock, California
M4.7
83 km
9 km
Aug 18, 1999
0 km S of Bolinas, California
M4.6
125 km
8 km
Mar 24, 1991
1 km NNE of Interlaken, California
M4.6
120 km
15 km
Sep 19, 2023
15 km SW of Westley, CA
M4.5
60 km
4 km
Jan 12, 2011
9 km SSE of San Juan Bautista, California
M4.5
136 km
8 km
Aug 3, 2006
5 km W of Glen Ellen, California
M4.5
124 km
9 km
Apr 4, 2023
1km NNW of Tres Pinos, CA
M4.4
131 km
10 km
Apr 28, 1990
3 km SSE of North Gate, California
M4.4
64 km
7 km
Apr 7, 1990
3 km SSE of North Gate, California
M4.4
64 km
8 km
Source: USGS Earthquake Catalog (M2.5+, 1990–2025). Sorted by magnitude.
Tornado History
82 tornadoes (EF0+) recorded within 100 km since 1950.
Strongest on record: EF2. Total: 4 injuries.
Date
Rating
Distance
Path
Fatalities
May 5, 1998
EF2
96 km
0.6 mi
0
Feb 7, 1978
EF2
82 km
1.9 mi
0
Apr 27, 1953
EF2
43 km
0.1 mi
0
Mar 11, 2023
EF1
65 km
0.8 mi
0
Jan 10, 2023
EF1
46 km
0.4 mi
0
Dec 24, 2015
EF1
82 km
6.2 mi
0
Nov 15, 2015
EF1
64 km
3.0 mi
0
Jan 23, 2010
EF1
45 km
1.6 mi
0
Apr 14, 2006
EF1
43 km
0.5 mi
0
Dec 16, 2002
EF1
97 km
1.3 mi
0
Dec 12, 1996
EF1
43 km
0.6 mi
0
Apr 19, 1988
EF1
23 km
0.2 mi
0
Apr 19, 1988
EF1
78 km
1.0 mi
0
Mar 22, 1983
EF1
83 km
2.0 mi
0
Jan 14, 1980
EF1
78 km
0.3 mi
0
Mar 4, 1978
EF1
72 km
1.0 mi
0
Mar 4, 1978
EF1
54 km
2.5 mi
0
Mar 1, 1978
EF1
45 km
1.5 mi
0
May 31, 1967
EF1
4 km
0.1 mi
0
Apr 1, 1958
EF1
71 km
2.0 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
80 km
1989
N. CALIFORNIA
Earthquake
1.0 m
62
118 km
1856
N. CALIFORNIA
Eruption + Earthquake
0.6 m
—
106 km
1906
N. CALIFORNIA
Eruption + Earthquake
0.1 m
—
113 km
1865
N. CALIFORNIA
Eruption + Earthquake
—
—
103 km
Source: NOAA/NCEI Historical Tsunami Database.
Nearby Volcanoes
4 volcanoes within 200 km.
Closest: Clear Lake (171 km).
Name
Type
Elevation
Last Eruption
Distance
Clear Lake
Volcanic field
1,439 m (4,721 ft)
Unknown
171 km
Mono Lake Volcanic Field
Pyroclastic cone(s)
2,121 m (6,959 ft)
1790
196 km
Mono-Inyo Craters
Lava dome(s)
2,796 m (9,173 ft)
1380
197 km
Mammoth Mountain
Lava dome(s)
3,369 m (11,053 ft)
1260
200 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
58 km
2015
BUTTE
72,894
67 km
2017
ATLAS
51,664
95 km
1987
PAPER
49,296
99 km
2007
LICK
47,424
85 km
2006
CANYON
36,851
69 km
1988
MILLER
35,750
88 km
1992
GULCH
18,019
72 km
2003
ANNIE
17,383
83 km
2024
CORRAL
16,138
42 km
2001
DARBY
14,734
87 km
2018
WAVERLY
12,238
37 km
2009
CORRAL
12,006
47 km
2001
CREEK
9,793
93 km
1992
MOCCASIN
9,565
86 km
1996
SCOTT
8,828
68 km
2015
WRAGG
8,455
90 km
2009
KNIGHT
8,140
93 km
2003
BIRD
7,727
48 km
2014
MONTICELLO
6,984
94 km
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
Month
Avg Temperature
Precipitation
Summary
January
49°F (9°C)
2.7 in
Wettest
February
51°F (11°C)
2.3 in
March
55°F (13°C)
2.3 in
April
60°F (15°C)
0.9 in
May
66°F (19°C)
0.4 in
June
72°F (22°C)
0.1 in
July
78°F (25°C)
0.0 in
Warmest, Driest
August
75°F (24°C)
0.1 in
September
72°F (22°C)
0.3 in
October
64°F (18°C)
0.8 in
November
53°F (12°C)
2.0 in
December
46°F (8°C)
2.0 in
Coldest
August has a seasonal temperature swing of 32°F / from 46°F in December to 78°F in July. Total annual precipitation is 14.0 inches, with January being the wettest month (2.7") and July the driest (0.0").