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

This page shows the average amount of rainfall per month in Sonoma (CA). The numbers are calculated over a 30-year period to provide a reliable average. Now, let’s break down all the details for a clearer picture.

Generally, Sonoma has a moderate amount of precipitation, averaging 644 mm of rainfall annually.

Monthly Precipitation Levels

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

The seasons in Sonoma, bring significant changes in precipitation. The wettest month, December, receives high rainfall, with an average of 134 mm of precipitation.

This rainfall is distributed across 12 rainy days. In contrast, the driest month, August, experiences much less rainfall, totaling 0.1 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 14°C and receives 160 hours of sunshine. During the driest month August you can expect a temperature of 29°C. For more detailed insights into the city’s temperatures, visit our Sonoma 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

Sonoma’s average annual precipitation is 644 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.

Osaka, Japan, experiences 1507 mm of rainfall annually, spread across the year with wetter summers.

Adelaide, Australia, enjoys 511 mm of annual precipitation, with dry summers and wet winters.

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