Palo Alto (CA) Monthly Rainfall & Precipitation

This page shows both the average monthly rainfall and the number of rainy days in Palo Alto, California, United States of America. The numbers reflect climate data gathered over a 30-year period, from 1990 to 2020. Now, let's explore all the details to give you a full picture.

Palo Alto's climate is marked by below-average rainfall, accumulating 351 mm (14 in) of precipitation yearly. The distribution includes a distinct dry season during certain months as shown in the precipitation charts below.

Monthly Precipitation Levels

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

Significant seasonal changes in precipitation occur throughout the year. During the wettest month, December receives substantial rainfall, averaging 83 mm (3.3 in) of precipitation, recorded across 12 rainy days.

In contrast, the driest month, July brings less rainfall, with 0 mm (0 in) over 0 rainy days.

December, the wettest month, has a maximum daytime temperature of 15°C (59°F). The city receives 160 hours of sunshine in this period. During the driest month July you can expect a temperature of 26°C (79°F). For more detailed insights into the city's temperatures, visit our Palo Alto Temperature page.

Palo Alto's average annual precipitation is 351 mm (14 in). Let's compare this to some popular worldwide tourist destinations:

The climate in San Francisco, USA, is influenced by coastal weather, with 469 mm (18 in) of rainfall mostly during the winter months.

In Shanghai, China, the annual average precipitation is 1347 mm (53 in), with a humid subtropical climate.

In Tokyo, Japan, the average annual precipitation is 1528 mm (60 in), with significant summer rains due to typhoon season.

Bangkok, Thailand, experiences a tropical monsoon climate with 1668 mm (66 in) of annual rainfall, with the heaviest precipitation occurring during September and October.

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.

Climate change is affecting precipitation patterns worldwide, including Palo Alto (CA):

• Changing Rainfall Patterns: Global warming causes drastic changes in the patterns of rainfall. Some areas have been experiencing increased frequency and intensity of rainfall, while other areas experience longer dry spells or even droughts.
• Local Impacts: Many regions are experiencing heavier rainfall in the winter months and drier, hotter summers. This affects agriculture, water resources, and ecosystems.

• "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 Palo Alto (CA)'s weather, including sunshine hours, humidity levels, and temperature data, visit our Palo Alto (CA) Climate page.