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

This page shows the average amount of rainfall per month in Riverside (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.

Riverside experiences desert-like conditions in terms of precipitation with almost no rainfall, generally receiving 193 mm annually.

Monthly Precipitation Levels

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

The seasons in Riverside, bring significant changes in precipitation. The wettest month, December, receives moderate rainfall, with an average of 62 mm of precipitation.

This rainfall is distributed across 7 rainy days. In contrast, the driest month, June, experiences much less rainfall, totaling 0 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 19°C and receives 205 hours of sunshine. During the driest month June you can expect a temperature of 31°C. For more detailed insights into the city’s temperatures, visit our Riverside 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

Riverside’s average annual precipitation is 193 mm. Let’s compare this to some popular worldwide tourist destinations:

In Barcelona, Spain, the average annual precipitation is 620 mm, evenly distributed across the year with no extreme wet or dry seasons.

In Shanghai, China, the annual average precipitation is 1347 mm, with a humid subtropical climate.

Melbourne, Australia, has 690 mm of rainfall annually, spread fairly evenly throughout the year.

Bangkok, Thailand, experiences a tropical monsoon climate with 1668 mm of annual rainfall, with the heaviest precipitation occurring during September and October.

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 Riverside (CA)’s weather, including sunshine hours, humidity levels, and temperature data, visit our Riverside (CA) Climate page.