Photo: User:Geographer · CC BY 2.5Fullerton’s winters are milder and less snowy than most of the U.S.
A typical July afternoon reaches 86°, a January night drops to 47°, and snow is almost unheard of.
A year in Fullerton at a glance
Each month’s typical high and low, and what it brings.
What stands out about Fullerton’s climate
Compared with towns across the U.S., with Fullerton’s place in California beside it.
What a year in Fullerton feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
Frost is rare
Frost and day counts come from Fullerton Muni Airport, Fullerton’s official weather station (the one in National Weather Service reports), 3 miles from the city’s center point, 140 ft lower.
The 2023 USDA map puts Fullerton’s center in zone 10a: the coldest night of a typical winter, averaged over 1991–2020, reaches about 35°. Plant labels use the zone; frost dates tell you when to plant.
90° days by month
Average days at 90° or more
About 13 inches of rain a year
February is the wettest month and August the driest. Rain falls on about 32 days a year. Snow is rare: about 0.0" in a normal year at Whittier City Yard Fc106c, CA, so most winters see none.
Rain + melted snow by month
Inches of water
Heating and cooling a home in Fullerton
41% of the work is heating, so air conditioning is the bigger bill. No month averages under 55°.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Fullerton Muni Airport.
Living with Fullerton’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
Zone 10a. Frost comes about 1 winter in 14, so tender plants can often stay out through winter.
Months with highs of 62–84° and lows of 40° or more: January, February, March, April, May, June, October, November and December. 39 miles of trails are waiting.
Parks & trails →Of the yearly building losses FEMA expects in Fullerton from natural hazards, earthquakes are the largest share (70%). Normals are averages; the hazards page covers the extremes.
Natural hazards →Fullerton and its neighbors
Anaheim the hottest July afternoons (88°, 2° warmer). Differences under a degree are within what the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Fullerton’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Fullerton, CA | 47° | 86° | 13" | 0.0" |
| Ewa Beach, HI | 62° | 87° | 17" | 0.0" |
| Port Isabel, TX | 52° | 92° | 26" | 0.2" |
| Sierra Vista Southeast, AZ | 32° | 91° | 15" | 0.7" |
| The Dalles, OR | 31° | 88° | 15" | 5.5" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Fullerton averaged 2.3° warmer than the 1900s. The biggest change is in January (+3.3°).
A bigger shift than in 98% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods. In a city of 139,000 people, part of the change is the city itself: pavement and buildings hold heat (the urban heat island).
How Fullerton compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Fullerton’s place among California’s.
Fullerton weather by month
Highs, lows and precipitation from NOAA’s grid at Fullerton’s center; snow, wet days and snow on the ground from Whittier City Yard Fc106c, CA. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 69° | 47° | 3.0" | 0.0" | 6 | 0 | 54° – 64° |
| February | 69° | 48° | 3.5" | 0.0" | 7 | 0 | 53° – 66° |
| March | 71° | 50° | 1.9" | 0.0" | 4 | 0 | 55° – 67° |
| April | 75° | 52° | 0.7" | 0.0" | 3 | 0 | 59° – 67° |
| May | 76° | 56° | 0.3" | 0.0" | 1 | 0 | 62° – 71° |
| June | 80° | 60° | 0.1" | 0.0" | 0 | 0 | 66° – 74° |
| July | 86° | 63° | 0.0" | 0.0" | 0 | 0 | 71° – 80° |
| August | 88° | 64° | 0.0" | 0.0" | 0 | 0 | 73° – 79° |
| September | 86° | 62° | 0.1" | 0.0" | 0 | 0 | 71° – 79° |
| October | 81° | 57° | 0.5" | 0.0" | 2 | 0 | 64° – 75° |
| November | 75° | 51° | 0.9" | 0.0" | 3 | 0 | 57° – 66° |
| December | 69° | 46° | 2.2" | 0.0" | 6 | 0 | 54° – 62° |
| Year | 77° | 55° | 13.0" | 0.0" | 32 | 0 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 53° to 66°. August is the most reliable, staying within 7°.
Where Fullerton’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Fullerton’s center.
- Snow: Whittier City Yard Fc106c, CA.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Fullerton Muni Airport, 3 miles from the city’s center point, 140 ft lower; the city’s official station.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Fullerton’s climate
What is the weather like in Fullerton?
A typical July afternoon reaches 86°, a January night drops to 47°, and snow is almost unheard of. Milder January nights than 95% of U.S. towns; hotter July afternoons than 54% of U.S. towns.
How cold does it get in Fullerton in winter?
December nights average 46°. A night at 32° or below comes in only some winters (0.3 a year on average). In the coldest December of the last 30 years the month averaged 54°.
How much snow does Fullerton get?
About 0.0 inches in a normal winter at Whittier City Yard Fc106c, CA, so most winters see none.
How hot does it get in Fullerton?
July, with a typical high of 86° and a low of 63°. About 39 days a year reach 90° and 4 reach 100° (Fullerton Muni Airport).
When is the first and last frost in Fullerton?
Most years have no frost at all: a 32° night comes in about 7% of winters at Fullerton Muni Airport, usually in December or January.
What growing zone is Fullerton in?
Zone 10a on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about 35°.
What is the best time of year to visit Fullerton?
By one simple rule (highs of 62–84° and lows of 40° or more), January, February, March, April, May, June, October, November and December. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Fullerton getting warmer?
Yes: 1991–2020 averaged 2.3° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 98% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Fullerton.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.