Fullerton, California climate: Normal weather by month, frost dates and records
Fullerton's normal year runs from 46°F December nights to 87°F August afternoons, with 11.9 inches of precipitation a year. (NOAA 1991-2020 normals)
In metric: a yearly mean of 19.0°C, December lows of 8°C, August highs of 30°C, 301 mm of precipitation a year.
- NOAA stationFullerton Municipal Airport
- Station IDUSW00003166
- Location33.87°N 117.98°W
- Elevation96 ft (29 m)
- From the center3 miles
- Population140,054
On October 23, the normal high in Fullerton is 79°F and the normal low 57°F, and the chance of measurable rain or snow is 11%.
Normals describe a typical year at the station, not a forecast. The National Weather Service forecast for Fullerton.
- Jan 69° 46°
- Feb 69° 48°
- Mar 71° 52°
- Apr 74° 54°
- May 76° 58°
- Jun 79° 63°
- Jul 84° 66°
- Aug 87° 66°
- Sep 85° 65°
- Oct 80° 58°
- Nov 74° 51°
- Dec 68° 46°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
What is the weather like in Fullerton each month?
August is the warmest month, with normal highs of 87°F; December the coldest, with normal lows of 46°F. The most precipitation falls in February (3.02 in), the least in July (0.02 in).
Each month has its own page with the day-by-day normals, the month's records and its recent years:
| Month | High | Low | Mean | Precip. | Wet days | 90°F days | Freezing nights | Daylight |
|---|---|---|---|---|---|---|---|---|
| January | 69°F | 46°F | 57.6°F | 2.85 | 5 | <1 | <1 | 10 h 10 min |
| February | 69°F | 48°F | 58.6°F | 3.02 | 7 | 1 | <1 | 11 h |
| March | 71°F | 52°F | 61.2°F | 1.74 | 5 | 1 | <1 | 11 h 50 min |
| April | 74°F | 54°F | 64.0°F | 0.59 | 4 | 2 | <1 | 13 h |
| May | 76°F | 58°F | 66.9°F | 0.30 | 2 | 2 | <1 | 13 h 50 min |
| June | 79°F | 63°F | 70.8°F | 0.08 | 1 | 2 | <1 | 14 h 20 min |
| July | 84°F | 66°F | 75.2°F | 0.02 | <1 | 6 | <1 | 14 h 10 min |
| August | 87°F | 66°F | 76.5°F | 0.02 | <1 | 9 | <1 | 13 h 30 min |
| September | 85°F | 65°F | 75.0°F | 0.14 | 1 | 9 | <1 | 12 h 30 min |
| October | 80°F | 58°F | 69.3°F | 0.50 | 3 | 6 | <1 | 11 h 20 min |
| November | 74°F | 51°F | 62.4°F | 0.74 | 5 | 2 | <1 | 10 h 30 min |
| December | 68°F | 46°F | 56.9°F | 1.86 | 6 | <1 | <1 | 10 h |
| Year (annual) | 76°F | 56°F | 66.2°F | 11.86 | 38 | 39 | <1 |
The same normals in °C and millimetres
| Month | High | Low | Mean | Precip. |
|---|---|---|---|---|
| January | 20°C | 8°C | 14.2°C | 72 mm |
| February | 21°C | 9°C | 14.8°C | 77 mm |
| March | 22°C | 11°C | 16.2°C | 44 mm |
| April | 23°C | 12°C | 17.8°C | 15 mm |
| May | 24°C | 15°C | 19.4°C | 8 mm |
| June | 26°C | 17°C | 21.6°C | 2 mm |
| July | 29°C | 19°C | 24.0°C | 1 mm |
| August | 30°C | 19°C | 24.7°C | 1 mm |
| September | 30°C | 18°C | 23.9°C | 4 mm |
| October | 27°C | 15°C | 20.7°C | 13 mm |
| November | 23°C | 10°C | 16.9°C | 19 mm |
| December | 20°C | 8°C | 13.8°C | 47 mm |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00003166; annual normals. Wet days: 0.01 inch or more; 90°F days and freezing nights: NOAA's day counts. Daylight: sunrise to sunset on the 15th, computed from the latitude.
When is the best weather to visit Fullerton?
Normal highs sit between 65°F and 85°F in January, February, March, April, May, June, July, October, November and December. Of those, July has the fewest days with rain (0).
That is a measurement, not a recommendation: it counts the months whose normal afternoon high sits between 65°F and 85°F, where a light layer is enough by day.
Source: NOAA NCEI 1991-2020 monthly normals, station USW00003166.
What hardiness zone is each Fullerton ZIP code in?
The USDA's 2023 map gives each ZIP code area one zone. Fullerton's 4 ZIP code areas run from zone 10a to 10b: 2 in 10a and 2 in 10b. Each ZIP's frost dates are in the frost tool.
Source: USDA 2023 Plant Hardiness Zone Map, ZIP listings: PRISM Group, Oregon State University, https://prism.oregonstate.edu, accessed October 8, 2026; ZIP areas in the place: Census Bureau 2020 ZCTA-to-place relationship file. A ZIP area counts when at least a tenth of its land (and 0.5 km²) lies in the place.
How hot and how cold does it get in Fullerton?
In a normal year in Fullerton, 39 days a year reach 90°F (4 of them 100°F or more), nights almost never fall to freezing and 38 days bring measurable precipitation.
- Days at 90°F or more
- 39a normal year
- Days at 100°F or more
- 4a normal year
- Nights at 32°F or colder
- fewer than 1a normal year
- Days that stay below freezing
- fewer than 1high of 32°F or less
- Days with 0.01 inch of precipitation
- 38a normal year
The highest temperature in this station's record (since 1998) is 116°F, on July 6, 2018; the lowest is 28°F, on January 14, 2007.
The wettest calendar year on that record is 2010, with 24.05 in.
Source: NOAA NCEI 1991-2020 annual normals, station USW00003166; records: ACIS (NOAA Regional Climate Centers), station USW00003166. Records use complete months only; a month missing more than three days is left out.
How sunny is Fullerton?
Over a year 87% of the sunlight that would reach the ground under clear skies gets through the clouds in the area around Fullerton, 5.4 kWh per square metre a day. August is the sunniest month (92%) and February the cloudiest (83%). Among the 459 U.S. places of 50,000 or more, that ranks tied 58th (with 22 others) in sunshine.
| Month | Share of clear-sky sunshine | Sunshine, kWh/m² a day |
|---|---|---|
| January | 85% | 3.3 |
| February | 83% | 4.1 |
| March | 85% | 5.4 |
| April | 86% | 6.5 |
| May | 83% | 6.9 |
| June | 85% | 7.3 |
| July | 89% | 7.4 |
| August | 92% | 7.0 |
| September | 91% | 6.0 |
| October | 88% | 4.6 |
| November | 87% | 3.6 |
| December | 83% | 2.9 |
Source: NASA POWER solar climatology, 2001-2020 (CERES SYN1deg). Satellite-based, for the 1-degree cell (about 100 km across) around the station, so it describes the area rather than the airport.
How much heating and cooling does Fullerton need?
A normal year in Fullerton brings 1,051 heating degree days, 80% fewer than the median U.S. place (5,373), and 1,507 cooling degree days, 66% more than the median (908). No month reaches 300 heating degree days. For gardens and crops, NOAA counts 5,940 growing degree days a year above 50°F.
| Month | Heating | Cooling |
|---|---|---|
| January | 235 | 5 |
| February | 187 | 10 |
| March | 138 | 22 |
| April | 78 | 48 |
| May | 27 | 86 |
| June | 2 | 176 |
| July | 0 | 318 |
| August | 0 | 358 |
| September | 1 | 300 |
| October | 16 | 150 |
| November | 113 | 33 |
| December | 254 | 2 |
| Year (annual) | 1,051 | 1,507 |
Source: NOAA NCEI 1991-2020 monthly normals, station USW00003166. A degree day is one degree of a day's mean temperature below 65°F (heating) or above it (cooling); utilities use them to estimate energy use.
Has Fullerton been warmer than normal lately?
2024 averaged 65.6°F, 0.6°F below the 1991-2020 normal of 66.2°F. 2 of the 4 complete years since 2021 ran warmer than the normal.
| Year | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 66.6°F | +0.4°F | 8.42 |
| 2022 | 67.4°F | +1.2°F | 5.76 |
| 2023 | 65.7°F | −0.5°F | 20.85 |
| 2024 | 65.6°F | −0.6°F | 14.72 |
Source: observed years: ACIS, station USW00003166. A year counts only with all twelve months complete.
How does Fullerton's climate compare?
Fullerton is warmer than 200 of the other 218 places with their own NOAA record in California, and wetter than 60. Across the 7,247 U.S. stations with normals, its annual mean of 66.2°F is warmer than 90%.
In the Köppen classification computed from these normals, Fullerton is BSh: hot semi-arid steppe. What the classes mean.
Places with the most similar year elsewhere
Measured month by month on the normal high, low and precipitation, among places of 20,000 or more people in other states:
Source: NOAA NCEI 1991-2020 normals for every station PlainClimate covers. Similarity: the root-mean-square difference of the 36 monthly figures, precipitation weighted so an inch counts like 6°F.
Which places near Fullerton share this climate record?
14 places have no NOAA station with 1991-2020 normals of their own, and this station is the nearest full record. A place's own climate can differ from these figures, by several degrees where it sits much higher or lower than the station, nearer the coast, or inside a large city's heat; for the larger places the next nearest records are named with their yearly mean, so the spread around them is visible, and places of 50,000 or more have their own page with NOAA's gridded normals.
- Norwalk, CAalso near: Long Beach (8 mi, 64.9°F a year); San Gabriel (12 mi, 66.0°F a year)98,230 people · 6 mi W
- Whittier, CAalso near: San Gabriel (9 mi, 66.0°F a year); Anaheim (12 mi, 67.7°F a year)85,589 people · 7 mi N
- Buena Park, CAalso near: Long Beach (9 mi, 64.9°F a year); Anaheim (9 mi, 67.7°F a year)82,611 people · 2 mi SW
- La Habra, CAalso near: Anaheim (8 mi, 67.7°F a year); Santa Ana Fire Station (14 mi, 66.1°F a year)61,391 people · 4 mi N
- South Whittier, CAalso near: Long Beach (11 mi, 64.9°F a year); San Gabriel (11 mi, 66.0°F a year)55,201 people · 5 mi NW
- Hacienda Heights, CAalso near: San Gabriel (10 mi, 66.0°F a year); Anaheim (12 mi, 67.7°F a year)54,956 people · 9 mi N
- Cypress, CA49,286 people · 5 mi SW
- Cerritos, CA46,851 people · 5 mi W
- La Mirada, CA46,367 people · 3 mi NW
- Stanton, CA41,188 people · 5 mi S
- Santa Fe Springs, CA18,683 people · 6 mi NW
- La Palma, CA15,092 people · 4 mi SW
- East Whittier, CA10,061 people · 4 mi N
- La Habra Heights, CA5,382 people · 6 mi N
Source: Census Bureau 2024 Gazetteer (place centers) and Vintage 2024 population estimates. Distance and direction from the station to each place's center.
Questions about Fullerton's climate
What is the coldest month in Fullerton?
December, with a normal high of 68°F and a normal low of 46°F. The warmest is August (87°F by day, 66°F at night).
What is the rainiest month in Fullerton?
February, with 3.02 in of precipitation in a normal year; the driest is July with 0.02 in.
What plant hardiness zone is Fullerton in?
The USDA's 2023 map puts Fullerton in zones 10a to 10b across its 4 ZIP code areas (10a in 92833, the largest). By the same method at Fullerton's NOAA station, the coldest night of a typical year reaches 35°F (22 years, 1991-2020): zone 10a.
Nearby and next
- Fullerton in OctoberThis month day by day, its records and recent years
- California climateThe statewide normals and every place in the state
- Anaheim, CA8 miles from this station, 67.7°F a year
- Long Beach, CA11 miles from this station, 64.9°F a year
- Santa Ana Fire Station, CA11 miles from this station, 66.1°F a year
- Santa Ana, CA15 miles from this station, 64.9°F a year
- Compare two placesMonth by month, side by side
Download these normals (CSV) · JSON · How these figures are made