May Weather in Fullerton, United States

Last updated: June 24, 2025

In Fullerton, United States during the month of May, the average temperature hovers around 16°C (61°F). However, temperatures can vary significantly, with a minimum of 0°C (33°F) and a maximum reaching up to 36°C (97°F). Expect some wet weather, as precipitation averages 142 mm (5.6 in) over 13 days, accompanied by an average humidity of 80%.

May Temperature in Fullerton

In May in Fullerton, the average temperature is 16°C (61°F). Maximum temperatures can reach 36°C (97°F), while minimums can drop as low as 0°C (33°F). Be prepared for a wide range of temperatures, making it essential to pack for both warm and cool conditions while traveling.

May Weather in Fullerton: Daily Temperature Highs, Lows, and Averages

The chart illustrates May temperature patterns in Fullerton, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Fullerton, May typically has an average temperature of 16°C (61°F), with highs reaching up to 36°C (97°F) and lows dropping to around 0°C (33°F).

Data source: Temperature data for Fullerton generated using information from the Copernicus Climate Change Service.

May Precipitation in Fullerton

In Fullerton in May, the precipitation amount is 142 mm (5.6 in) spread over 13 days.

May Precipitation Trends in Fullerton

The chart displays monthly precipitation patterns in Fullerton, with values for each month alongside May’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how May’s conditions compare to those of other months. In Fullerton, May typically receives around 142 mm (5.6 inches) of precipitation spread over approximately 13 days.

Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

May Humidity in Fullerton

In Fullerton in May, humidity is 80%. With an average temperature of 16°C (61°F), this humidity feels like a warm blanket wrapped around you, making sightseeing a sweat-inducing challenge but also lending a lush vibrancy to the surroundings that can enhance your travel experience.

May Average Humidity in Fullerton

This chart illustrates the average monthly humidity levels in Fullerton, with May’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In May, average humidity in Fullerton is approximately 80%, offering insight into how humid the weather typically is during this month.

Data source: Humidity data for May generated using information from the Copernicus Climate Change Service.

May UV Index in Fullerton

In Fullerton in May, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Fullerton.

Maximum UV Index Levels in Fullerton for May

The chart shows the monthly maximum UV Index (UVI) for Fullerton in May, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In May, the maximum UV index in Fullerton typically reaches 10, which falls under the very high exposure category.

Data source: Fullerton May UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

Extreme (11+): Avoid the sun, stay in shade.
Very High (8-10): Limit sun exposure.
High (6-7): Use SPF 30+ and protective clothing.
Moderate (3-5): Midday shade recommended.
Low (0-2): No protection needed.

How May Weather in Fullerton Compares to Other Months

Weather in Fullerton varies notably across the year, with each month offering distinct climate conditions. This page compares May’s weather to other months in Fullerton, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in Fullerton, showing how May’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-4°C (26°F)	28 mm (1.1 inches)	73%	moderate
February Weather	-4°C (25°F)	20 mm (0.8 inches)	81%	moderate
March Weather	4°C (40°F)	89 mm (3.5 inches)	69%	high
April Weather	9°C (49°F)	57 mm (2.2 inches)	71%	very high
May Weather	16°C (61°F)	142 mm (5.6 inches)	80%	very high
June Weather	24°C (75°F)	97 mm (3.8 inches)	83%	extreme
July Weather	25°C (78°F)	65 mm (2.5 inches)	84%	very high
August Weather	23°C (74°F)	84 mm (3.3 inches)	84%	very high
September Weather	20°C (69°F)	57 mm (2.2 inches)	77%	very high
October Weather	11°C (52°F)	83 mm (3.3 inches)	72%	high
November Weather	4°C (40°F)	22 mm (0.9 inches)	80%	moderate
December Weather	-1°C (31°F)	42 mm (1.6 inches)	79%	moderate