San Antonio (TX) Rainfall & Precipitation: Monthly Averages and Year-Round Insights

This page shows both the average monthly rainfall and the number of rainy days in San Antonio, Texas, United States of America. The figures are based on a 30-year period (1990–2020) to provide a reliable average. Now, let’s explore all the details to give you a full picture.

Generally, San Antonio has a moderate amount of precipitation, averaging 818 mm of rainfall annually.

Monthly Precipitation Levels

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

The seasons in San Antonio, bring significant changes in precipitation. The wettest month, May, receives high rainfall, with an average of 130 mm of precipitation.

This rainfall is distributed across 9 rainy days. In contrast, the driest month, December, experiences much less rainfall, totaling 34 mm over 8 rainy days. These distinct seasonal differences provide diverse experiences throughout the year.

May, the wettest month, has a maximum daytime temperature of 31°C. The city receives 222 hours of sunshine in this period. During the driest month December you can expect a temperature of 18°C. For more detailed insights into the city’s temperatures, visit our San Antonio 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

San Antonio’s average annual precipitation is 818 mm. Let’s compare this to some popular worldwide tourist destinations:

Boston, USA, experiences 1238 mm of annual precipitation, including significant snowfall during the winter.

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

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

Ho Chi Minh City, Vietnam, receives 1955 mm of annual rainfall, with a pronounced wet season from May to November, typical of its tropical monsoon climate.

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.

Global Warming and Precipitation

Climate change is affecting precipitation patterns worldwide, including San Antonio (TX):

• 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.

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