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Contents
- The climate of Fullerton
- The best time to visit Fullerton
- The worst time to visit Fullerton
- Spring weather in Fullerton
- Summer weather in Fullerton
- Autumn weather in Fullerton
- Winter weather in Fullerton
- Weather in January
- Weather in February
- Weather in March
- Weather in April
- Weather in May
- Weather in June
- Weather in July
- Weather in August
- Weather in September
- Weather in October
- Weather in November
- Weather in December
- Frequently asked questions
- Average temperature
- Average pressure
- Average wind speed
- Average humidity
- Average rainfall
- Average rainfall days
- Average daylight
- Average sunshine
- Average sunshine days
- Average UV index
- Average cloud cover
- Average visibility
Trees and neat lawns of the famous Muckenthaler Community Center in Fullerton, California
The climate of Fullerton
Situated squarely in the Mediterranean climate zone, Fullerton, California experiences what the Köppen climate classification refers to as a hot-summer Mediterranean climate (Csa). This particular climatic category denotes not only sunshine filled summers but also relatively cool, clement winters.
Throughout the year, temperatures in Fullerton vary quite significantly. The coldest month is January, with average low temperatures of 50.9°F (10.5°C), while August is the most sweltering, featuring average high temperatures skyrocketing to 83.5°F (28.6°C). A glance at the yearly relative humidity shows the driest month to be November, with a reading of 51%, in sharp contrast to the most humid periods noted in June and July at 65%.
Precipitation patterns in Fullerton depict an interesting narrative. Maximum rainfall of 1.54" (39mm) occurs in December, while the driest period is in June, with a mere 0.04" (1mm) of rainfall. The variation in the duration of daylight hours ranges between 14.4 hours in June, the longest day, to 9.9 hours in December, the shortest. Average UV index values climb to their highest at 6 from June to September, heralding increased potential for sunburn.
Throughout the year, temperatures in Fullerton vary quite significantly. The coldest month is January, with average low temperatures of 50.9°F (10.5°C), while August is the most sweltering, featuring average high temperatures skyrocketing to 83.5°F (28.6°C). A glance at the yearly relative humidity shows the driest month to be November, with a reading of 51%, in sharp contrast to the most humid periods noted in June and July at 65%.
Precipitation patterns in Fullerton depict an interesting narrative. Maximum rainfall of 1.54" (39mm) occurs in December, while the driest period is in June, with a mere 0.04" (1mm) of rainfall. The variation in the duration of daylight hours ranges between 14.4 hours in June, the longest day, to 9.9 hours in December, the shortest. Average UV index values climb to their highest at 6 from June to September, heralding increased potential for sunburn.
The best time to visit Fullerton
Judging by weather conditions, Fullerton can best be visited between May and October. This period is marked by maximum daylight hours, stretching the days to brim with exploration opportunities. Temperatures are undeniably warm, peaking in August at 83.5°F (28.6°C), but rarely stifling. Humidity levels prove manageable, staying between 59% and 65%.
Summer months offer maximum sunshine, with the hours of direct sunlight ranging from 11.9 hours in June, 12 hours in July and 12 hours in August. UV index during this time reaches 6, necessitating adequate sun protection measures, especially from June to September. With rainfall levels at their lowest during this period, it stands to reason that a visitor is less likely to encounter wet weather disruptions to outdoor plans.
Summer months offer maximum sunshine, with the hours of direct sunlight ranging from 11.9 hours in June, 12 hours in July and 12 hours in August. UV index during this time reaches 6, necessitating adequate sun protection measures, especially from June to September. With rainfall levels at their lowest during this period, it stands to reason that a visitor is less likely to encounter wet weather disruptions to outdoor plans.
The worst time to visit Fullerton
January through March tends to be less ideal for visiting Fullerton. The temperature lows dwell around the 50°F (10°C) mark, potentially discouraging outdoor activities for visitors accustomed to warmer conditions. While these temperatures may not be exceedingly harsh, the shortened daylight hours from December, offering only 9.9 hours, to February's 11 hours may limit sightseeing opportunities.
Meanwhile, relative humidity climbs to its peak at 59% in February, which may contribute to a damp feel in the chilly winter air. Furthermore, the highest rainfall measures are observed within these months, with February laying claim to 1.26" (32mm). A visitor during this period needs to be prepared to brave sporadic rain showers.
Meanwhile, relative humidity climbs to its peak at 59% in February, which may contribute to a damp feel in the chilly winter air. Furthermore, the highest rainfall measures are observed within these months, with February laying claim to 1.26" (32mm). A visitor during this period needs to be prepared to brave sporadic rain showers.
Spring weather in Fullerton
Spring in Fullerton ushers in a warming trend that begins in March. Temperatures during this season steadily rise from lows of 52°F (11.1°C) in March to a delightful 66.2°F (19°C) in May. Embracing the spring spirit, the duration of daylight begins to lengthen, starting with 12 hours in March and extending to 13.9 hours in May.
Average UV index in spring is 5, suggesting moderate exposure. Rainfall levels reduce substantially during this season, dropping from 0.87" (22mm) in March to as low as 0.2" (5mm) in May. This sits alongside declining cloud coverage, with percentages appearing from 22% and reducing to 17% by the end of spring.
Average UV index in spring is 5, suggesting moderate exposure. Rainfall levels reduce substantially during this season, dropping from 0.87" (22mm) in March to as low as 0.2" (5mm) in May. This sits alongside declining cloud coverage, with percentages appearing from 22% and reducing to 17% by the end of spring.
Summer weather in Fullerton
Summer in Fullerton is a time of consistently high temperatures. The mercury climbs from June's average high of 76.6°F (24.8°C), peaking impressively at 83.5°F (28.6°C) in August. This season is characterized by an abundance of daylight hours, with June offering the longest day at 14.4 hours.
Sunny days abound in summer, ensuring bountiful sunshine from 11.9 hours in June to 12 hours in July and August. UV index values also peak during these months at 6, making it imperative for visitors to take precautions against skin damage. Despite the heat, summer qualifies as the driest season with rainfall measuring a negligible 0.04" (1mm) in June.
Sunny days abound in summer, ensuring bountiful sunshine from 11.9 hours in June to 12 hours in July and August. UV index values also peak during these months at 6, making it imperative for visitors to take precautions against skin damage. Despite the heat, summer qualifies as the driest season with rainfall measuring a negligible 0.04" (1mm) in June.
Autumn weather in Fullerton
Autumn in Fullerton witnesses temperatures from a pleasantly warm 82.2°F (27.9°C) in September to a relatively cool 64°F (17.8°C) by the close of November. Beginning with 12.4 hours of daylight in September, duration shortens to 10.4 hours in November.
Rainfall begins to increase modestly from 0.2" (5mm) in September to 0.63" (16mm) in November. Notably, levels of relative humidity start to wind down during this season, transitioning from 58% in September to 51% in November - the driest period in the year.
Rainfall begins to increase modestly from 0.2" (5mm) in September to 0.63" (16mm) in November. Notably, levels of relative humidity start to wind down during this season, transitioning from 58% in September to 51% in November - the driest period in the year.
Winter weather in Fullerton
Winter in Fullerton is relatively mild, with temperatures ranging from 64°F (17.8°C) in December to a low of 50.9°F (10.5°C) in January. Daylight hours continue to decrease slashing to 9.9 hours in December before slowly clawing back to 10.2 hours in February.
Rainfall measures certainly pick up during winter, with an impressive peak of 1.54" (39mm) in December. Meanwhile, relative humidity values maintain their steady rise, starting from 55% in December. The UV index drops to 4, indicating moderate exposure from the sun during winter.
Rainfall measures certainly pick up during winter, with an impressive peak of 1.54" (39mm) in December. Meanwhile, relative humidity values maintain their steady rise, starting from 55% in December. The UV index drops to 4, indicating moderate exposure from the sun during winter.
Weather in January
January in Fullerton, California presents favorable weather with moderate temperatures. The cooler temperatures from 51.4°F (10.8°C) to 66.2°F (19°C) make it a great time for outdoor enthusiasts to explore the city. There is relatively less rainfall this month as compared to December and the forthcoming month of February. Weather in January »
Weather in February
February retains a similar temperature range as January with slight fluctuations. Although no extreme change is observed from the previous month, February witnesses slightly elevated rainfall at 1.26" (32mm). The weather remains comfortable despite slightly higher relative humidity at 59% as compared to January. Weather in February »
Weather in March
As Fullerton transitions from winter to spring in March, it experiences a minor increase in both temperatures and rainfall. Temperatures rise gently to 52°F (11.1°C) to 67.6°F (19.8°C) with slightly higher rainfall than February. Weather in March »
Weather in April
April brings to Fullerton, California, warmer temperatures than March and significantly diminished rainfall, signifying the arrival of spring. The monthly average highs hit 70.5°F (21.4°C) and rainfall gets nearly halved to 0.47" (12mm). Weather in April »
Weather in May
May continues the trend of rising temperatures with high averages reaching 72.3°F (22.4°C) and lower temperatures at 56.1°F (13.4°C). The rainfall dips even further to just 0.2" (5mm), making May the month with low rainfall in the first half of the year. Weather in May »
Weather in June
June marks the official onset of summer in Fullerton, California with a noticeable rise in temperature. The maximum temperature averages reach 76.6°F (24.8°C), making it one of the warmer months of the year. The sliding scale of rainfall shows a significant drop in June to only 0.04" (1mm) and offers an optimal outdoor experience. Weather in June »
Weather in July
July sets the stage as the hottest month in Fullerton with average high temperatures soaring to 81.5°F (27.5°C). But, residents and visitors need not worry about sweltering heat as the city records the lowest relative humidity of 61%. Weather in July »
Weather in August
August is one month Fullerton, California gets to experience the highest average temperatures reaching 83.5°F (28.6°C). Nonetheless, the rainfall remains minimal at around 0.2" (5mm) and maintains a dry atmosphere conducive for diverse outdoor activities. Weather in August »
Weather in September
September receives residual summer warmth as recorded with a high temperature of 82.2°F (27.9°C), although a downward trend from August. There is no drastic increase in the amount of rainfall which stands at 0.2" (5mm), reaffirming the continuous dry spell. Weather in September »
Weather in October
October brings noticeable changes in the weather with an average high temperature decreasing to 77.5°F (25.3°C). The rain starts to pick up marginally in October to 0.28" (7mm), making it a wetter month than September. This gradual shift towards slightly cooler conditions sets the pace for the impending winter season. Weather in October »
Weather in November
November in Fullerton, California is characterized by cooler temperatures and a steady increase in precipitation. The comfortable high of 71.4°F (21.9°C) and rainfall of 0.63" (16mm) indicate the entrance of late fall. This month has noticeably cooler weather, with less daylight and increased cloud cover as compared to October. Weather in November »
Weather in December
December marks the advent of winter with the lowest average temperatures recorded from 50.9°F (10.5°C) to 64°F (17.8°C). As compared to November, substantial rainfall is seen in December, going as high as 1.54" (39mm). As the temperature drops, rain increases, marking a significant change from the previous month. Weather in December »
Updated: Jul 26, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How much does it rain?
In Fullerton, during the entire year, the rain falls for 52.5 days and collects up to 7.09" (180mm) of precipitation.
What is the month with the lowest UV index?
January, February, November and December, with an average maximum UV index of 4, are months with the lowest UV index.
When is Daylight Saving Time (DST)?
On Sunday, March 10. 2024, at 2:00 am, Daylight Saving Time starts, and the time zone changes from PST to PDT. Daylight Saving Time ends Sunday, November 3. 2024, at 2:00 am, and the time zone reverts from PDT to PST.
What is the most humid month?
The most humid month is June, with an average relative humidity of 65%.
What is the driest month?
The month with the least rainfall is June, when the rain falls for 1.5 days and typically collects 0.04" (1mm) of precipitation.
When are the longest days?
With an average of 14h and 24min of daylight, June has the longest days of the year.
What is the month with the highest UV index?
June through September, with an average maximum UV index of 6, are months with the highest UV index.
What are the months with the most sunshine?
The months with the most sunshine are July and August, with an average of 12h of sunshine.
What time of the year is the hottest?
August, with average temperatures reaching a high of 83.5°F (28.6°C) and a low of 65.5°F (18.6°C), is the warmest month.
What is the least humid month?
With an average relative humidity of 51%, November is the least humid month.
What time of the year is the coldest in Fullerton?
December proves to be the coldest month, recording an average maximum temperature of 64°F (17.8°C) and a minimum temperature of 50.9°F (10.5°C).
What is the wettest month?
The month with the most rainfall is December, when the rain falls for 6.6 days and typically aggregates up to 1.54" (39mm) of precipitation.
What is the month with the shortest days?
With an average of 9h and 54min of daylight, December has the shortest days of the year.
What is the month with the least sunshine?
With an average of 6.7h of sunshine, December has the least sunshine of the year.
Average temperature
Fullerton, CA
The warmest month (with the highest average high temperature) is August (83.5°F).
The month with the lowest average high temperature is December (64°F).
The month with the highest average low temperature is August (65.5°F).
The coldest month (with the lowest average low temperature) is February (50.2°F).
Average pressure
Fullerton, CA
- Average pressure in January:
30.1"Hg - Average pressure in February:
30.05"Hg - Average pressure in March:
30.03"Hg - Average pressure in April:
29.96"Hg - Average pressure in May:
29.92"Hg - Average pressure in June:
29.88"Hg
- Average pressure in July:
29.91"Hg - Average pressure in August:
29.89"Hg - Average pressure in September:
29.89"Hg - Average pressure in October:
29.95"Hg - Average pressure in November:
30.03"Hg - Average pressure in December:
30.07"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed
Fullerton, CA
- Average wind speed in January:
5.2mph - Average wind speed in February:
5.2mph - Average wind speed in March:
5.3mph - Average wind speed in April:
6mph - Average wind speed in May:
5.8mph - Average wind speed in June:
5.3mph
- Average wind speed in July:
5.1mph - Average wind speed in August:
4.8mph - Average wind speed in September:
4.7mph - Average wind speed in October:
4.7mph - Average wind speed in November:
5mph - Average wind speed in December:
5.1mph
The windiest month (with the highest average wind speed) is April (6mph).
The calmest months (with the lowest average wind speed) are September and October (4.7mph).
Average humidity
Fullerton, CA
The month with the highest relative humidity is June (65%).
The month with the lowest relative humidity is November (51%).
Average rainfall
Fullerton, CA
- Average rainfall in January:
1.14" - Average rainfall in February:
1.26" - Average rainfall in March:
0.87" - Average rainfall in April:
0.47" - Average rainfall in May:
0.2" - Average rainfall in June:
0.04"
The wettest month (with the highest rainfall) is December (1.54").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days
Fullerton, CA
- Average rainfall days in January:
4.8 days - Average rainfall days in February:
5.3 days - Average rainfall days in March:
7.3 days - Average rainfall days in April:
5.7 days - Average rainfall days in May:
4 days - Average rainfall days in June:
1.5 days
- Average rainfall days in July:
3.9 days - Average rainfall days in August:
2.2 days - Average rainfall days in September:
3.5 days - Average rainfall days in October:
3.5 days - Average rainfall days in November:
4.2 days - Average rainfall days in December:
6.6 days
The month with the highest number of rainy days is March (7.3 days).
The month with the least rainy days is June (1.5 days).
Average daylight / Average sunshine
Fullerton, CA
- Average daylight in January:
10h and 1min - Average daylight in February:
11h and 0min - Average daylight in March:
12h and 0min - Average daylight in April:
13h and 1min - Average daylight in May:
13h and 5min - Average daylight in June:
14h and 2min
- Average daylight in July:
14h and 1min - Average daylight in August:
13h and 2min - Average daylight in September:
12h and 2min - Average daylight in October:
11h and 2min - Average daylight in November:
10h and 2min - Average daylight in December:
9h and 5min
The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 9h and 54min).
- Average sunshine in January:
6h and 5min - Average sunshine in February:
6h and 5min - Average sunshine in March:
8h and 5min - Average sunshine in April:
11h and 0min - Average sunshine in May:
11h and 2min - Average sunshine in June:
11h and 5min
- Average sunshine in July:
12h and 0min - Average sunshine in August:
12h and 0min - Average sunshine in September:
10h and 4min - Average sunshine in October:
8h and 3min - Average sunshine in November:
7h and 1min - Average sunshine in December:
6h and 4min
The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The month with the least sunshine is December (Average sunshine: 6h and 42min).
Average sunshine days
Fullerton, CA
- Average sunshine days in January:
25.2 days - Average sunshine days in February:
20.6 days - Average sunshine days in March:
22.9 days - Average sunshine days in April:
22.3 days - Average sunshine days in May:
23.6 days - Average sunshine days in June:
24.3 days
- Average sunshine days in July:
24.3 days - Average sunshine days in August:
25.8 days - Average sunshine days in September:
23.4 days - Average sunshine days in October:
24.6 days - Average sunshine days in November:
24.2 days - Average sunshine days in December:
23.2 days
The month with the most sunshine days is August (25.8 days).
The month with the least sunshine days is February (20.6 days).
Average UV index
Fullerton, CA
The months with the highest UV index are June, July, August and September (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 4).
Average cloud cover
Fullerton, CA
The months with the most cloud cover are March and December (Cloud cover 22).
The month with the least cloud cover is August (Cloud cover 5).
Average visibility
Fullerton, CA
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Fullerton, California, USA
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