San Francisco Rainfall & Precipitation: Monthly Averages and Year-Round Insights

This page shows the average amount of rainfall per month in San Francisco. 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.

San Francisco tends toward drier weather patterns, receiving approximately 482 mm of rain per year.

Monthly Precipitation Levels

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

Significant seasonal changes in precipitation occur throughout the year. During the wet season, December receives substantial rainfall, averaging 74 mm of precipitation, recorded across 13 rainy days.

In contrast, the drier season, July brings less rainfall, with 1.5 mm over 2 rainy days.

December, the city’s wettest month, has a maximum daytime temperature of 17°C. During the driest month July you can expect a temperature of 28°C. For more detailed insights into the city’s temperatures, visit our San Francisco Temperature page.

Annual Precipitation in Spain

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

Amsterdam Precipitation Compared World Wide

San Francisco’s average annual precipitation is 482 mm. Let’s compare this to some popular worldwide tourist destinations:

In Toronto, Canada, annual precipitation averages [964 mm], with snowy winters and rainy summers.

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

Perth, Australia, receives 565 mm of rainfall annually, mostly during the winter months.

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.

How Does Precipitation Affect Local Climate?

Precipitation has a very strong role in determining the local climate and ecosystem:

• Rainy Seasons: Many parts of the world have well-defined wet seasons where precipitation is distinctly higher. These are normally accompanied by lush vegetation and temperature patterns.
• Dry Seasons: In areas where the climate is either desert or Mediterranean, the amount of precipitation is drastically reduced, leading to a shortage of water and arid conditions.

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