San Francisco (CA) Monthly Rainfall & Precipitation

This page shows both the average monthly rainfall and the number of rainy days in San Francisco, California, United States of America. The numbers reflect climate data gathered over a 30-year period, from 1990 to 2020. Now, let's break down all the details for a clearer picture.

San Francisco typically sees modest rainfall throughout the year, with an average annual precipitation of 469 mm (18 in). The city experiences a distinct dry season during certain months, as illustrated in the graph below.

Monthly Precipitation Levels

The average number of days each month with precipitation (> 0.2 mm (0.01 in))

The climate in San Francisco shows significant variation throughout the year. Expect 112 mm (4.4 in) of precipitation during the wettest month December, distributed over 13 rainy days.

In contrast, July offers drier and sunnier days, with around 0.4 mm (0.02 in) of rainfall over a single rainy day.

December, the wettest month, has a maximum daytime temperature of 14°C (57°F). The city receives 160 hours of sunshine in this period. During the driest month July you can expect a temperature of 22°C (72°F). For more detailed insights into the city's temperatures, visit our San Francisco Temperature page.

San Francisco's average annual precipitation is 469 mm (18 in). Let's compare this to some popular worldwide tourist destinations:

In Lisbon, Portugal, the average annual precipitation is 774 mm (30 in), characterized by wet winters and dry summers typical of the Mediterranean climate.

Beijing, China, receives 560 mm (22 in) of annual precipitation, concentrated in the summer months.

Perth, Australia, receives 565 mm (22 in) of rainfall annually, mostly during the winter months.

Kuala Lumpur, Malaysia, receives 2529 mm (100 in) of annual rainfall, characteristic of its equatorial tropical rainforest climate, with consistent rainfall throughout the year and peak months during March and November.

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.

• "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 (15 inches) wide and 20 cm (7.9 inches) 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 (103 feet) fell during the winter of 1972.

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