Fullerton (CA) Rainfall & Precipitation: Monthly Averages and Year-Round Insights

This page shows the average amount of rainfall per month in Fullerton (CA). The numbers are calculated over a 30-year period to provide a reliable average. Now, let’s explore all the details to give you a full picture.

Fullerton experiences desert-like conditions in terms of precipitation with almost no rainfall, generally receiving 242 mm annually.

Monthly Precipitation Levels

The average number of days each month with precipitation (> 0.2 mm)

The seasons in Fullerton, bring significant changes in precipitation. The wettest month, December, receives moderate rainfall, with an average of 67 mm of precipitation.

This rainfall is distributed across 8 rainy days. In contrast, the driest month, August, experiences much less rainfall, totaling 0.3 mm over 0 rainy days. These distinct seasonal differences provide diverse experiences throughout the year.

December, the city’s wettest month, has a maximum daytime temperature of 20°C and receives 205 hours of sunshine. During the driest month August you can expect a temperature of 31°C. For more detailed insights into the city’s temperatures, visit our Fullerton Temperature page.

Annual Precipitation in the United States of America

The map below shows the annual precipitation across the United States of America. You can also select the different months in case you are interested in a specific month.

Amsterdam Precipitation Compared World Wide

Fullerton’s average annual precipitation is 242 mm. Let’s compare this to some popular worldwide tourist destinations:

New York City, USA, receives 1276 mm of rainfall annually, with precipitation evenly distributed throughout the year.

Beijing, China, receives 560 mm of annual precipitation, concentrated in the summer months.

In Tokyo, Japan, the average annual precipitation is 1528 mm, with significant summer rains due to typhoon season.

Kuala Lumpur, Malaysia, receives 2529 mm of annual rainfall, characteristic of its equatorial tropical rainforest climate, with consistent rainfall throughout the year and peak months during March and November.

How is Precipitation Measured?

Precipitation amounts are measured using specific gauges installed at weather stations, collecting both rain and snow and any other type of precipitation. Rainfall is measured directly in millimeters, while that from snow and ice is obtained by melting it. Automated systems often incorporate heaters to make this easier.

Information from these stations is transmitted via Wi-Fi, satellite, GPS, or telephone connections to central monitoring networks. This information is immediately updated and integrated into weather models and forecasts.

Interesting weather facts

• "Ginger" was the longest-lasting Atlantic tropical storm, which spun around the open ocean for 28 days in 1971.
• The world's largest snowflake was recorded in the Guinness Book of Records, at 38 cm wide and 20 cm thick. The snowflake fell at Fort Keogh, Montana, USA, on 28 January 1887.
• The greatest snowfall recorded was on Mt. Rainier, Washington State, USA—over 31.5 meters fell during the winter of 1972.

For more detailed information about Fullerton (CA)’s weather, including sunshine hours, humidity levels, and temperature data, visit our Fullerton (CA) Climate page.