Weather & Climate in Byron, CA

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

Byron enjoys a temperate climate with an average annual temperature of 64°F (18°C). Winters average 48°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 12.4 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 36 feet.

Temperature

48°F Jan (9°C) 78°F Jul (25°C)

Annual Average	63.5°F
	18% above US avg
January Average	48°F (9°C)
July Average	78°F (25°C)
Sunny Days	330 days/yr

Geography

Elevation	36 ft (11 m)
Area	6.5 sq mi (16.8 km²)
Population Density	288/sq mi
Coordinates	37.8756°N, 121.6421°W
Timezone	America/Los_Angeles
County	Contra Costa County County
Nearest Airport	Metro Oakland International (OAK) 33 miles away

Precipitation & Snow

Annual Rainfall 12.4"

67% below US avg

Snowfall 0.0"

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	99.5 / 100
Social Vulnerability	21.5 / 100
Community Resilience	67.8 / 100

Hazard Breakdown

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

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

Earthquake History

5,906 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	70 km	11 km
Apr 18, 1990	5 km NNW of Aromas, California	M5.4	105 km	5 km
Aug 12, 1998	10 km SW of Ridgemark, California	M5.1	126 km	9 km
Apr 18, 1990	4 km E of Interlaken, California	M5.1	102 km	7 km
Jan 16, 1993	9 km E of Gilroy, California	M4.9	97 km	7 km
Apr 18, 1990	4 km NNW of Aromas, California	M4.9	105 km	6 km
Apr 23, 1995	22 km NNE of Soledad, California	M4.9	147 km	7 km
Sep 3, 2000	5 km WSW of Yountville, California	M4.9	88 km	9 km
Apr 19, 1996	2 km E of Aromas, California	M4.9	110 km	5 km
May 14, 2002	5 km SSW of Gilroy, California	M4.9	101 km	7 km
Sep 4, 1995	13 km SW of Middletown, California	M4.8	132 km	7 km
May 12, 2006	7 km W of Cobb, California	M4.7	146 km	4 km
Apr 18, 1990	4 km N of Aromas, California	M4.7	105 km	4 km
May 21, 1996	8 km ESE of East Foothills, California	M4.7	58 km	8 km
Aug 11, 1993	14 km ESE of Alum Rock, California	M4.7	63 km	9 km
Jan 2, 2025	4 km NW of Cobb, CA	M4.7	145 km	1 km
Aug 27, 2011	21 km NE of Soledad, California	M4.6	149 km	8 km
Mar 24, 1991	1 km NNE of Interlaken, California	M4.6	102 km	15 km
Aug 18, 1999	0 km S of Bolinas, California	M4.6	92 km	8 km
Jan 11, 2000	6 km N of Geyserville, California	M4.6	149 km	6 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: 10 injuries.

Date	Rating	Distance	Path	Fatalities
May 5, 1998	EF2	66 km	0.6 mi	0
Feb 7, 1978	EF2	93 km	1.9 mi	0
Apr 27, 1953	EF2	62 km	0.1 mi	0
Jan 11, 1951	EF2	70 km	5.7 mi	0
Dec 14, 2024	EF1	98 km	0.3 mi	0
Mar 11, 2023	EF1	98 km	0.8 mi	0
Jan 10, 2023	EF1	81 km	0.4 mi	0
Nov 15, 2015	EF1	83 km	3.0 mi	0
Jan 23, 2010	EF1	12 km	1.6 mi	0
Apr 14, 2006	EF1	62 km	0.5 mi	0
Mar 20, 2005	EF1	73 km	3.0 mi	0
May 5, 1998	EF1	69 km	0.3 mi	0
Dec 12, 1996	EF1	71 km	0.6 mi	0
Apr 19, 1988	EF1	54 km	0.2 mi	0
Apr 19, 1988	EF1	99 km	1.0 mi	0
Mar 22, 1983	EF1	97 km	2.0 mi	0
Jan 14, 1980	EF1	49 km	0.3 mi	0
Mar 4, 1978	EF1	86 km	1.0 mi	0
Mar 4, 1978	EF1	76 km	2.5 mi	0
Mar 1, 1978	EF1	67 km	1.5 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	45 km
1989	N. CALIFORNIA	Earthquake	1.0 m	62	96 km
1856	N. CALIFORNIA	Eruption + Earthquake	0.6 m	—	71 km
1906	N. CALIFORNIA	Eruption + Earthquake	0.1 m	—	78 km
1865	N. CALIFORNIA	Eruption + Earthquake	—	—	79 km

Source: NOAA/NCEI Historical Tsunami Database.

Nearby Volcanoes

1 volcano within 200 km. Closest: Clear Lake (156 km).

Name	Type	Elevation	Last Eruption	Distance
Clear Lake	Volcanic field	1,439 m (4,721 ft)	Unknown	156 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	44 km
2020	CZU AUG LIGHTNING	85,894	96 km
2017	NUNS	56,883	92 km
2017	ATLAS	51,664	75 km
2007	LICK	47,424	75 km
2006	CANYON	36,851	63 km
1988	MILLER	35,750	73 km
2003	ANNIE	17,383	80 km
2024	CORRAL	16,138	31 km
2018	WAVERLY	12,238	71 km
2009	CORRAL	12,006	34 km
1985	LEXINGTON	11,550	85 km
1996	SCOTT	8,828	93 km
2015	WRAGG	8,455	77 km
2003	BIRD	7,727	45 km
2014	MONTICELLO	6,984	83 km
1984	SITE 300 3	6,911	29 km
2005	TESLA	6,638	25 km
2003	DEL PUERTO	6,441	54 km
2016	COLD	6,289	83 km

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

Monthly Weather

Month	Avg Temperature	Precipitation	Summary
January	48°F (9°C)	2.5 in	Wettest
February	51°F (11°C)	2.1 in
March	55°F (13°C)	1.7 in
April	59°F (15°C)	0.8 in
May	65°F (18°C)	0.3 in
June	70°F (21°C)	0.1 in
July	78°F (25°C)	0.0 in	Warmest, Driest
August	73°F (23°C)	0.1 in
September	70°F (21°C)	0.2 in
October	64°F (18°C)	0.8 in
November	54°F (12°C)	1.8 in
December	46°F (8°C)	1.8 in	Coldest

Byron has a seasonal temperature swing of 32°F / from 46°F in December to 78°F in July. Total annual precipitation is 12.3 inches, with January being the wettest month (2.5") and July the driest (0.0").

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