Hyperlocal rainfall totals + real-time NOAA forecasts
Accurate weather without the clutter
Fullerton, CA Weather by Month and Climate Averages
Monthly normals · Rain · Snow
Sunshine · Freeze dates · Records · Best time to visit
What is the weather like in Fullerton, CA?
Fullerton, CA gets 11.9 in of precipitation a year over about 38 rainy days. August is the warmest month (average high 87°F) and January the coldest (average low 46°F).
Semi-arid climate
Fullerton, CA has hot summers and warm winters. Daytime highs range from about 69°F in December to 87°F in August. February is usually the wettest month. The most comfortable time to visit is typically January, March to June, and November to December, when daytime highs sit near 73°F.
| Season | Months | Avg low | Avg high |
|---|---|---|---|
| Winter | Dec–Feb | 47° | 69° |
| Spring | Mar–May | 54° | 74° |
| Summer | Jun–Aug | 65° | 84° |
| Autumn | Sep–Nov | 58° | 80° |
How much rain does Fullerton get?
Fullerton gets 11.9 in of precipitation in an average year, spread over about 38 days with measurable rain. That is fewer rainy days than 89% of the US.
February is the wettest month, with 3.0 in. July is the driest, with 0.0 in. February has the most rainy days, about 7.
The longest dry spell in the last five years lasted 180 days, to November 1, 2024.
From September 2025 to August 2026 Fullerton got 15.8 in of rain, against a normal of 11.9 in for those months. November 2025 had the most, with 5.4 in.
See where Fullerton ranks: rainiest cities in the US, US cities with the most rainy days, rainiest cities in California.
Fullerton weather by month
Fullerton weather in January
In January, Fullerton averages a high of 70°F and a low of 46°F. It gets 2.9 in of precipitation over about 5 rainy days. Estimated sunshine is 53% of daylight hours, derived from ERA5 cloud cover. The January record high is 94°F (2003) and the record low is 28°F (2007). January is one of the most comfortable months to visit.
Fullerton weather in February
In February, Fullerton averages a high of 69°F and a low of 48°F. It gets 3.0 in of precipitation over about 7 rainy days. Estimated sunshine is 60% of daylight hours, derived from ERA5 cloud cover. The February record high is 94°F (2016) and the record low is 35°F (2002).
Fullerton weather in March
In March, Fullerton averages a high of 71°F and a low of 51°F. It gets 1.7 in of precipitation over about 5 rainy days. Estimated sunshine is 52% of daylight hours, derived from ERA5 cloud cover. The March record high is 100°F (2026) and the record low is 36°F (2006). March is one of the most comfortable months to visit.
Fullerton weather in April
In April, Fullerton averages a high of 74°F and a low of 54°F. It gets 0.6 in of precipitation over about 4 rainy days. Estimated sunshine is 55% of daylight hours, derived from ERA5 cloud cover. The April record high is 102°F (2022) and the record low is 39°F (1999). April is one of the most comfortable months to visit.
Fullerton weather in May
In May, Fullerton averages a high of 76°F and a low of 58°F. It gets 0.3 in of precipitation over about 2 rainy days. Estimated sunshine is 48% of daylight hours, derived from ERA5 cloud cover. The May record high is 104°F (2004) and the record low is 46°F (1999). May is one of the most comfortable months to visit.
Fullerton weather in June
In June, Fullerton averages a high of 80°F and a low of 62°F. It gets 0.1 in of precipitation over about 1 rainy days. Estimated sunshine is 56% of daylight hours, derived from ERA5 cloud cover. The June record high is 109°F (2016) and the record low is 52°F (1999). June is one of the most comfortable months to visit.
Fullerton weather in July
In July, Fullerton averages a high of 85°F and a low of 66°F. It gets 0.0 in of precipitation over about 0 rainy days. Estimated sunshine is 71% of daylight hours, derived from ERA5 cloud cover. The July record high is 116°F (2018) and the record low is 58°F (2001).
Fullerton weather in August
In August, Fullerton averages a high of 87°F and a low of 66°F. It gets 0.0 in of precipitation over about 0 rainy days. Estimated sunshine is 71% of daylight hours, derived from ERA5 cloud cover. The August record high is 107°F (2020) and the record low is 56°F (2010).
Fullerton weather in September
In September, Fullerton averages a high of 85°F and a low of 64°F. It gets 0.1 in of precipitation over about 1 rainy days. Estimated sunshine is 68% of daylight hours, derived from ERA5 cloud cover. The September record high is 113°F (2024) and the record low is 54°F (2013).
Fullerton weather in October
In October, Fullerton averages a high of 81°F and a low of 58°F. It gets 0.5 in of precipitation over about 3 rainy days. Estimated sunshine is 66% of daylight hours, derived from ERA5 cloud cover. The October record high is 107°F (2017) and the record low is 45°F (2009).
Fullerton weather in November
In November, Fullerton averages a high of 75°F and a low of 51°F. It gets 0.7 in of precipitation over about 5 rainy days. Estimated sunshine is 66% of daylight hours, derived from ERA5 cloud cover. The November record high is 99°F (2010) and the record low is 34°F (2010). November is one of the most comfortable months to visit.
Fullerton weather in December
In December, Fullerton averages a high of 69°F and a low of 46°F. It gets 1.9 in of precipitation over about 6 rainy days. Estimated sunshine is 48% of daylight hours, derived from ERA5 cloud cover. The December record high is 87°F (2017) and the record low is 31°F (1998). December is one of the most comfortable months to visit.
Sunshine, humidity and wind in Fullerton
July is the sunniest month in Fullerton, with estimated sunshine of 71% of daylight hours from ERA5 cloud cover. May is the cloudiest, at 48%. The annual cloud-cover estimate is 60% of daylight hours; it is not a measurement of sunshine duration. Fullerton is sunnier than 85% of the US.
Humidity peaks in May at 72% and is lowest in November at 59%.
Wind averages 4 mph over the year, and April is the windiest month at 4 mph.
Fullerton has about 38 days a year above 90°F. Fullerton is hotter than 60% of the US.
Thunderstorms occur on about 5 days a year.
See where Fullerton ranks: sunniest cities in the US, cloudiest cities in the US, hottest cities in the US.
Fullerton weather records
These records cover FULLERTON MUNI AP during 1998–2026. Earlier records or other stations in the city may differ.
The hottest temperature on record at the Fullerton station is 116°F, on July 6, 2018. The coldest is 28°F, on January 14, 2007.
The wettest day in the available station history brought 2.8 in of precipitation, on January 22, 2017.
The best time to visit Fullerton
The most comfortable time to visit is typically January, March to June, and November to December, when daytime highs sit near 73°F.
Winter (December–February) is warm, with average highs around 69°F and lows near 47°F.
Spring (March–May) is warm, with average highs around 74°F and lows near 54°F.
Summer (June–August) is hot, with average highs around 84°F and lows near 65°F. It can feel humid.
Autumn (September–November) is warm, with average highs around 80°F and lows near 58°F.
Monthly climate
| Month | Average low | Average high | Precip | Rain days | Wind | Humidity | Estimated sunshine | Record high | Record low |
|---|---|---|---|---|---|---|---|---|---|
| January | 46° | 70° | 2.9 in | 5 | 3 mph | 68% | 53% | 94° | 28° |
| February | 48° | 69° | 3.0 in | 7 | 4 mph | 60% | 60% | 94° | 35° |
| March | 51° | 71° | 1.7 in | 5 | 4 mph | 68% | 52% | 100° | 36° |
| April | 54° | 74° | 0.59 in | 4 | 4 mph | 68% | 55% | 102° | 39° |
| May | 58° | 76° | 0.30 in | 2 | 4 mph | 72% | 48% | 104° | 46° |
| June | 62° | 80° | 0.08 in | 1 | 4 mph | 70% | 56% | 109° | 52° |
| July | 66° | 85° | 0.02 in | 0 | 4 mph | 70% | 71% | 116° | 58° |
| August | 66° | 87° | 0.02 in | 0 | 4 mph | 70% | 71% | 107° | 56° |
| September | 64° | 85° | 0.14 in | 1 | 3 mph | 70% | 68% | 113° | 54° |
| October | 58° | 81° | 0.50 in | 3 | 3 mph | 67% | 66% | 107° | 45° |
| November | 51° | 75° | 0.74 in | 5 | 3 mph | 59% | 66% | 99° | 34° |
| December | 46° | 69° | 1.9 in | 6 | 3 mph | 67% | 48% | 87° | 31° |
Station: FULLERTON MUNI AP, 6 km from the city. Temperature normal baseline: 1991–2020, calculated from available NOAA GHCN-Daily observations. Available station history: 1998–2026; record values refer to this station and period, not the entire city’s history. Precipitation includes rain and the water equivalent of frozen precipitation; snowfall depth is shown separately when available. Sources and methods
From ERA5 reanalysis. Sunshine is estimated from cloud cover.
Fullerton climate questions
How much rain does Fullerton get?
Fullerton gets 11.9 in of precipitation in an average year, over about 38 rainy days.
What is the wettest month in Fullerton?
February is the wettest month in Fullerton, with 3.0 in. July is the driest, with 0.0 in.
How many rainy days does Fullerton have a year?
Fullerton has about 38 days with measurable rain in an average year. February has the most, about 7.
What is the hottest month in Fullerton?
August is the warmest month in Fullerton, with an average high of 87°F.
What is the coldest month in Fullerton?
January is the coldest month in Fullerton, with an average low of 46°F.
What is the record high temperature in Fullerton?
Within the available 1998–2026 station history, the record high at the Fullerton station is 116°F, set on July 6, 2018. The record low is 28°F, on January 14, 2007.
What is the sunniest month in Fullerton?
July is the sunniest month in Fullerton, with estimated sunshine of 71% of daylight hours from ERA5 cloud cover. May is the cloudiest.
What is the best time to visit Fullerton?
The most comfortable time to visit is typically January, March to June, and November to December, when daytime highs sit near 73°F.