Annual Average Number of Rainy Days

San Antonio receives an average of about 41 rainy days per year. It is a region where rain falls evenly throughout the year, averaging about 3-5 days of rain each month.

This is moderate compared to other cities in Texas. Rain mainly falls in spring and fall, with sudden downpours characteristic of the summer season.

Winter is relatively dry, but rain can occur occasionally with cold snaps. Snow is extremely rare.

Monthly Average Rainfall

The monthly average rainfall in San Antonio varies greatly by season. Below is a summary of the average rainfall for each month:

• January: about 2.5 inches of rain.
• February: about 2.3 inches of rain.
• March: about 3.0 inches of rain.
• April: about 2.8 inches of rain.
• May: about 3.5 inches of rain.
• June: about 4.0 inches of rain.
• July: about 3.8 inches of rain.
• August: about 4.2 inches of rain.
• September: about 3.6 inches of rain.
• October: about 3.0 inches of rain.
• November: about 2.7 inches of rain.
• December: about 2.4 inches of rain.

Characteristics:

• Spring (March to May): Spring is a time when rainfall gradually increases. In particular, strong thunderstorms often occur in May as a precursor to summer rains.

• Summer (June to August): Summer is the time when San Antonio records the most rainfall. Due to high temperatures and humidity, sudden weather changes like thunderstorms frequently occur.

• Fall (September to November): Fall still sees relatively high rainfall, but there is a tendency to become drier.

• Winter (December to February): Winter is relatively dry, with low rainfall. However, rain can occasionally occur with cold snaps.

Highest Recorded Rainfall

The highest recorded rainfall in San Antonio was during Tropical Storm Claudette from August 19 to 20, 1979, when 15.89 inches (about 403mm) fell. This rainfall resulted from a concentrated downpour over a short period, causing severe flooding throughout the city. The recorded amount during Claudette was 15.89 inches (about 403mm).