San Antonio sits at the edge of “Flash Flood Alley,” a stretch of south-central Texas notorious for some of the most extreme rainfall rates in the country, where warm Gulf moisture collides with the Balcones Escarpment and can dump enormous amounts of rain in just a few hours. The city averages around 810 mm (about 32 inches) of rain a year, but individual storms have produced record-breaking totals that overwhelm the region’s many normally-dry creeks with little warning. This combination of hilly terrain and thin soil means water runs off fast rather than soaking in. Because flash flooding here can develop faster than a standard forecast can capture, radar tracking is treated as a critical, routinely used safety tool. NWS Doppler radar KEWX (Austin/San Antonio) covers the region.
Rain in San Antonio by month
San Antonio gets about 779 mm (30.7 in) of rain in an average year. The wettest month is May, with 100 mm (3.9 in), and the driest is February, with 36 mm (1.4 in).
| Month | Average rain | Average temperature |
|---|---|---|
| January | 49 mm (1.9 in) | 10.1 °C (50 °F) |
| February | 36 mm (1.4 in) | 12.4 °C (54 °F) |
| March | 61 mm (2.4 in) | 16.8 °C (62 °F) |
| April | 62 mm (2.5 in) | 21.1 °C (70 °F) |
| May | 100 mm (3.9 in) | 24.9 °C (77 °F) |
| June | 71 mm (2.8 in) | 28.2 °C (83 °F) |
| July | 71 mm (2.8 in) | 29.0 °C (84 °F) |
| August | 62 mm (2.4 in) | 29.6 °C (85 °F) |
| September | 95 mm (3.8 in) | 26.0 °C (79 °F) |
| October | 78 mm (3.1 in) | 21.3 °C (70 °F) |
| November | 49 mm (1.9 in) | 15.7 °C (60 °F) |
| December | 45 mm (1.8 in) | 11.1 °C (52 °F) |
Long-term monthly averages from NASA POWER (MERRA-2 satellite reanalysis). They describe the wider area around San Antonio and can differ slightly from local weather-station records.
Learn more: Flash Flood Warning Signs on Radar · Open the full Rain Map
Frequently Asked Questions
Is it raining in San Antonio right now?
The map above shows recent radar observations over San Antonio, Texas where coverage is available. Use the map legend and timestamp to interpret the imagery. A blank map over San Antonio can mean no detected precipitation, missing coverage, delayed data, or rain too light for radar to detect.
How often does the San Antonio rain radar update?
Updates depend on the radar provider and local network. Check the timestamp on the map for the latest available frame, and press play to compare recent observations. Radar imagery can lag conditions on the ground.
Can I see if a storm is heading toward San Antonio?
Press play to compare recent radar frames over Texas and see the direction of detected rain. This can help you assess approaching showers near San Antonio, but storms can grow or change direction; check your local weather service for forecasts and warnings.
Is this San Antonio rain radar free to use?
Yes, completely free – no account, app download, or sign-up required. It works in any browser on desktop and mobile.