Fullerton, CA Climate: Temperature & Rain by Month
Average temperature and precipitation from NOAA NCEI 1991–2020 normals →, with a derived climate comfort score
30-year climate normals (1991-2020) from Fullerton's primary NOAA station, FULLERTON MUNI AP.
The climate verdict for Fullerton
Dryness leads the climate profile for Fullerton, California, with 11.9 inches of precipitation a year. NOAA records an annual average of 66°F. August is the warmest month at 77°F and December the coldest at 57°F.
- 66°F
- annual average temperature (NOAA normal)
- 11.9"
- yearly precipitation total
Fullerton: NOAA 1991-2020 normals describe a typical year, not a forecast. Method: /methodology.
Normals record plate
Sheet USW00003166 · Fullerton, CA 66°F mean · 11.9" precip
TEMP-MILD · RANK-WARM · PHOTO-FINISH · PRCP-ARID · SWING-NARROW · COMF-UNK · LOAD-MIX · STN-1 · BOOK-FULL
- TEMP-MILD 66°F
- RANK-WARM #6,175
- PHOTO-FINISH ≈ Anvil Rch
- PRCP-ARID 11.9"
- SWING-NARROW 20°F
- COMF-UNK Comfort n/a
- LOAD-MIX H/C balanced
- STN-1 USW00003166
- BOOK-FULL 5/6 fields
Nearest mean-temperature peer: Anvil Rch, AZ (+ 0 °F mean)
Instrument codes from this station's NOAA 1991–2020 normals, mean temperature, corpus warmth rank, photo-finish peer station, precipitation band, seasonal swing, comfort composite, degree-day load, and field book, not a livability rating.
Mean-temperature neighbourhood
Nationwide NOAA normal poles and nearest peers, not a reprint of every CA station list.
- Fullerton (this station) 66°F
- Hot Crockett, TX 66°F
- Near Anvil Rch, AZ 66°F
- Near Bakersfield, CA 66°F
- Near Baxley, GA 66°F
Climate Living Index · Fullerton
Fullerton: 79/100 · grade B
Fullerton publishes 3 of 6 Living Index dimensions (NOAA annual/seasonal normals · NOAA daily multivariate normals); 3 missing weights rescale to 100.
PlainClimate-derived for Fullerton, not an official NOAA rating. Breakpoints and limits.
| Dimension | Station value | Score |
|---|---|---|
| Normal heat + freeze calendar | 0 calendar days | 100/100 · A |
| Annual temperature balance | 66.2°F · 1.3° from 67.5°F | 95/100 · A |
| Precipitation balance | 11.9 in · 23.1 from 35 in | 18/100 · F |
Fullerton · 2026-08-04 · NOAA NCEI Climate Normals · method .
Fullerton's normals sit in a dry climate class: BSh
Precipitation is low relative to temperature but above true desert thresholds: hot semi-arid steppe (BSh). Class BSh is the Peel et al. (2007) label for this station's monthly mean temperature and precipitation normals: dry (arid or semi-arid), specifically hot semi-arid steppe.
- Köppen code
- BSh
- Group
- Dry (arid or semi-arid)
- Warmest month
- 76.5°F
- Coldest month
- 56.9°F
Source: official public datasets monthly normals (1991–2020) at the city’s primary station. This is a station classification, not a mapped regional consensus.
National standing · balanced station
Where Fullerton sits across the climate record
Three NOAA fields for Fullerton's primary station, temperature, precipitation, and seasonal swing, are ranked against every station-mapped normal that carries the same field.
- Annual temperature
- Top 10% warmest
- Among 6,861 stations, Fullerton sits in the warmer third of annual means.
- Annual precipitation
- Drier than 90%
- Fullerton's annual total ranks in the drier third of 6,352 measured normals.
- Seasonal temperature swing
- Narrower than 97%
- Warmest-to-coldest month gap for Fullerton is compact versus 6,861 complete station-years.
Monthly Temperatures
Average daily high and low temperatures by month
| Month | Avg High | Avg Low | Mean | Precip | Freeze Days | 90°F+ Days |
|---|---|---|---|---|---|---|
| January | 69°F (20°C) | 46°F (8°C) | 58°F (14°C) | 2.9" | 0.1 | 0.1 |
| February | 69°F (21°C) | 48°F (9°C) | 59°F (15°C) | 3.0" | 0.0 | 0.5 |
| March | 71°F (22°C) | 52°F (11°C) | 61°F (16°C) | 1.7" | 0.0 | 1.0 |
| April | 74°F (23°C) | 54°F (12°C) | 64°F (18°C) | 0.6" | 0.0 | 1.6 |
| May | 76°F (24°C) | 58°F (15°C) | 67°F (19°C) | 0.3" | 0.0 | 1.8 |
| June | 79°F (26°C) | 63°F (17°C) | 71°F (22°C) | 0.1" | 0.0 | 2.1 |
| July | 84°F (29°C) | 66°F (19°C) | 75°F (24°C) | 0.0" | 0.0 | 6.4 |
| August | 87°F (30°C) | 66°F (19°C) | 77°F (25°C) | 0.0" | 0.0 | 9.4 |
| September | 85°F (30°C) | 65°F (18°C) | 75°F (24°C) | 0.1" | 0.0 | 9.1 |
| October | 80°F (27°C) | 58°F (15°C) | 69°F (21°C) | 0.5" | 0.0 | 5.6 |
| November | 74°F (23°C) | 51°F (10°C) | 62°F (17°C) | 0.7" | 0.0 | 1.8 |
| December | 68°F (20°C) | 46°F (8°C) | 57°F (14°C) | 1.9" | 0.1 | 0.0 |
The year, day by day
The calendar barely moves in Fullerton: no date carries a normal high of 90°F or a normal low at freezing. The year runs between 45°F near December 16 and 87°F near August 26.
No freezing date
Not one calendar date in the 1991–2020 record carries a normal low at or below 32°F. The coldest normal low of the year is 45°F around December 16.
Where the wet dates fall
The likeliest wet date is February 19, when 24% of years recorded at least a hundredth of an inch. The driest is August 7 at 1%. Summed across the calendar, that is about 39 wet dates a year.
The widest day
November 8 carries the biggest normal gap between afternoon and dawn, 24°F between the normal high and the normal low.
Look up any date
Any date's 1991–2020 normal for Fullerton.
Where Fullerton Stands Nationally
A drier-than-most normal water year — around 12 inches, below what four out of five ranked stations collect.
Fullerton earns one nationally notable standing (outer quintile) against 6,860 NOAA 1991–2020 normals stations, middle-of-the-pack metrics stay silent here.
Monthly Precipitation
Average monthly rainfall
5.2 days with precipitation
6.8 days with precipitation
5.3 days with precipitation
3.5 days with precipitation
1.8 days with precipitation
0.5 days with precipitation
0.3 days with precipitation
0.2 days with precipitation
0.8 days with precipitation
3.0 days with precipitation
4.6 days with precipitation
6.3 days with precipitation
Fullerton's wet season runs through the cold months
December, January and February carry 65% of the year's precipitation here, while June through August contribute 1%. That is the cool-season-dominant pattern of the West Coast and the higher inland West, where storm tracks swing south in winter and summer turns dry; the thermometer meanwhile shows an unusually narrow 19.6°F seasonal spread.
- Wettest month
- February, 3.0"
- Driest month
- August, 0.0"
- Wettest three months
- February, January, December (65% of the year)
Shares are computed from this station's own 1991-2020 monthly precipitation normals. A cool-season label means the December-February share reaches 35%. Where snow falls, the monthly figures above report liquid-equivalent precipitation, so a wet winter month is not necessarily a rainy one.
How Fullerton's precipitation splits across the calendar
About 38 days a year record measurable precipitation here, carrying 11.9" between them, or roughly 0.31 inches on a typical wet day. That sits in the middle band: neither the many-light-days pattern of the Pacific Northwest and the Great Lakes, nor the few-heavy-events pattern of the Gulf and the desert Southwest.
A wet day is one recording at least 0.01 inches. These are 1991-2020 normals: they describe an average year and say nothing about the heaviest single storm on record.
Frost Dates & Growing Season
First Fall Freeze
N/A
50% probability date
Last Spring Freeze
N/A
50% probability date
Heating & Cooling Degree Days
Annual totals indicate energy demand for heating and cooling
Heating Degree Days
1,051
Higher = more heating needed
Cooling Degree Days
1,507
Higher = more cooling needed
Warmest Month
August
Coldest Month
December
Nationwide similar cities
Other rankable U.S. places outside CA closest to Fullerton on two NOAA annual-normal axes (mean temperature and annual precipitation). Chip rows use distinct link sets.
Closest by average temperature
Nearest out-of-state peers by annual mean temperature (66°F here).
- Baxley, GA 66°F · 0.0°F off
- Crockett, TX 66°F · 0.0°F off
- El Paso, TX 66°F · 0.0°F off
- Homerville, GA 66°F · 0.0°F off
Closest by annual precipitation
Nearest out-of-state peers by annual precipitation (11.9" here), excluding temperature-peer places.
- Boulder, UT 11.8" · 0.0" off
- Pinedale, WY 11.9" · 0.0" off
- Rudyard, MT 11.9" · 0.0" off
- Ovando, MT 11.8" · 0.1" off
Scarce-water calendar
Where Fullerton's limited precipitation lands
mixed demand · dry · low swing
Local precipitation is sparse in this otherwise mixed profile. The station reports 11.9 inches annually, within PlainClimate's dry band. Snowfall is not added to the interpretation because its annual value is missing. The monthly distribution matters because the total alone does not reveal the timing.
The calendar stays thermally compact and dry. August and December mark the typical warm and cold ends of the calendar, only 19.6°F apart, while the annual precipitation total remains below PlainClimate's dry threshold. The annual average is 66°F. The monthly rows show whether that limited precipitation is spread through the year or concentrated in a shorter interval.
Fullerton combines a compact 19.6°F annual temperature range with meaningful demand on both sides of the thermostat: 1,051 heating and 1,507 cooling degree days. The balance matters more here than either annual total in isolation.
A frost-free growing-season length is not available for Fullerton. That missing field is kept separate from the observed temperature and precipitation record rather than filled from a regional estimate.
Fullerton wettest normal
February
February concentrates the scarce annual total (11.9 inches).
Fullerton driest normal
July
July is typically driest; arid stations are defined by when water is absent, not by a four-season grid.
Questions about Fullerton's climate
How dry is Fullerton? ▼
How many days above 90°F does Fullerton get? ▼
How much energy does heating and cooling require in Fullerton? ▼
Data Sources
Data source: NOAA U.S. Climate Normals v1.0.1 (1991-2020). All figures on this page are from Fullerton's primary station: FULLERTON MUNI AP (USW00003166). For informational purposes only.
Place identity: U.S. Census Bureau 2024 Gazetteer places. The 2024 Census Gazetteer identifies the exact name-and-state match as an incorporated place (GEOID 0628000). Match rule for Fullerton: exact normalized name + state only, no fuzzy expansion, so nearby differently spelled facilities stay unmatched.
On this page every temperature, precipitation, and derived score for Fullerton comes from its primary NOAA station record. No figure on this page is typed in by an editor - each value is rendered from NOAA 1991-2020 U.S. Climate Normals. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 1991–2020 normals.