What is the hottest month in Fullerton, CA?

August is the warmest month, with a normal high of 87°F at Fullerton MUNI AP.

What is the coldest month in Fullerton, CA?

December is the coldest month, with a normal low of 46°F.

What is the wettest month in Fullerton, CA?

February has the most precipitation on average, about 3.02 inches.

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Checked Oct 25, 2026

Fullerton, CA Climate

1991 to 2020 normals at Fullerton MUNI AP, 3.5 mi from the center of Fullerton, elevation 96 ft.

Average weather by month

Select a month for daily normals and last year's weather

Month	High	Low	Precip.	Snow
January	69°	46°	2.85 in	--
February	69°	48°	3.02 in	--
March	71°	52°	1.74 in	--
April	74°	54°	0.59 in	--
May	76°	58°	0.30 in	--
June	79°	63°	0.08 in	--
July	84°	66°	0.02 in	--
August	87°	66°	0.02 in	--
September	85°	65°	0.14 in	--
October	80°	58°	0.50 in	--
November	74°	51°	0.74 in	--
December	68°	46°	1.86 in	--
Year	76°		11.86 in	--

Frequently asked questions

What is the hottest month in Fullerton, CA?: August is the warmest month, with a normal high of 87°F at Fullerton MUNI AP.
What is the coldest month in Fullerton, CA?: December is the coldest month, with a normal low of 46°F.
What is the wettest month in Fullerton, CA?: February has the most precipitation on average, about 3.02 inches.

Today

Fullerton, CA forecast

Data sources

U.S. Climate Normals 1991-2020NOAA National Centers for Environmental Information · Official site
U.S. Climate Normals 1991-2020 (daily) and GHCN-Daily via Access Data ServiceNOAA National Centers for Environmental Information · Official site

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About this data

Weather and emergencies: Weather, air quality and hazard information on this page is delayed and may be incomplete. It is not a substitute for official warnings. Always follow the National Weather Service, local emergency management and public safety officials. In an emergency, call 911. For evacuation orders, use your local official alert system.

Climate normals are 30-year averages measured at one weather station, which may be miles from the place named here or at a different elevation.

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