October Weather in Fullerton, United States

Last updated: June 24, 2025

In October, the average temperature in Fullerton, United States hovers around 11°C (52°F). Expect a range of -8°C (17°F) to 33°C (92°F), offering a diverse climate experience. During this period, precipitation averages 83 mm (3.3 in) spread over 9 days, while humidity sits at a comfortable 72%.

October Temperature in Fullerton

In October in Fullerton, the average temperature is 11°C (52°F). Maximums can reach 33°C (92°F), and minimums can drop as low as -8°C (17°F). Be prepared for a wide range of temperatures if you plan to visit during this time.

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

The chart illustrates October 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, October typically has an average temperature of 11°C (52°F), with highs reaching up to 33°C (92°F) and lows dropping to around -8°C (17°F).

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

October Precipitation in Fullerton

In Fullerton in October, the precipitation amount is 83 mm (3.3 in) over the course of 9 days.

October Precipitation Trends in Fullerton

The chart displays monthly precipitation patterns in Fullerton, with values for each month alongside October’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how October’s conditions compare to those of other months. In Fullerton, October typically receives around 83 mm (3.3 inches) of precipitation spread over approximately 9 days.

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

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

October Humidity in Fullerton

In Fullerton in October, humidity is 72%. With an average temperature of 11°C (52°F), this humidity feels like a damp chill that can make outdoor activities uncomfortable, often leaving travelers feeling slightly cold and clammy unless they are dressed in layers.

October Average Humidity in Fullerton

This chart illustrates the average monthly humidity levels in Fullerton, with October’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In October, average humidity in Fullerton is approximately 72%, offering insight into how humid the weather typically is during this month.

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

October UV Index in Fullerton

In Fullerton in October, the maximum UV index is 6, which corresponds to a high Exposure Category. The time to burn is approximately 25 minutes. To find the hourly UV index in Fullerton, you can refer to this Hourly UV Index in Fullerton.

Maximum UV Index Levels in Fullerton for October

The chart shows the monthly maximum UV Index (UVI) for Fullerton in October, 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 October, the maximum UV index in Fullerton typically reaches 6, which falls under the high exposure category.

Data source: Fullerton October 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 October 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 October’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 October’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