San Antonio weather in September
September in San Antonio: sweltering, a little rain, with clean air — a great time to visit.
#8 of 12 months in San Antonio · #426 of 604 destinations to visit in September · comfort 70/100 (tier B)
Updated June 2026 · climate normals from ERA5 reanalysis
San Antonio climate normals — September
| Daytime high | 34°C / 93°F | 🔥 sweltering |
|---|---|---|
| Nighttime low | 23°C / 74°F | |
| Feels like (high) | 36°C / 97°F | |
| Rainfall | 44 mm / 1.7 in | 🌦 some rain |
| Rainy days | 6 days | |
| Humidity | 59% | 🍃 comfortable |
| Dew point | 19°C / 66°F | |
| Sunshine | 10.7 h/day | |
| Daylight | 12.3 h | |
| Wind | 16 km/h / 10 mph | |
| Air quality (US AQI) | 42 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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San Antonio in September — FAQ
- Is September a good time to visit San Antonio?
- September in San Antonio: sweltering, a little rain, with clean air — a great time to visit. It ranks #8 of 12 months for San Antonio on SeasonMap's comfort score (70/100).
- What is the weather like in San Antonio in September?
- In September, San Antonio averages a daily high of 33.8°C and a low of 23.4°C, with about 44.3 mm of rain over roughly 6.4 rainy days.
- What is the air quality in San Antonio in September?
- San Antonio has a mean US Air Quality Index of about 42 in September.