San Antonio Weather in September
September in San Antonio averages 33°C (91°F) during the day and 21°C (70°F) at night. Quite a bit of rainfall is typical this month, with around 102 mm (4 in) on average. An umbrella is a good idea.
Rainfall in San Antonio in September
Expect around 9 days of rain based on historical data, with 102 mm (4 in) average. Rainfall intensity is on the higher side this month. Expect more substantial showers rather than light, passing rain.
Temperature in San Antonio in September
Daytime highs in San Antonio in September reach 33°C (91°F), with nights around 21°C (70°F). Mornings and evenings are often more comfortable than the peak afternoon hours. With lows of 21°C (70°F), the nights are warm and generally comfortable.
Sunshine in San Antonio in September
With approximately 235 hours of sunshine, the days are filled with clear skies. It makes it a perfect month for being outside.September in San Antonio has its charm. However, if you're seeking pleasant, dry and sunny weather, our weather planner can help you explore other destinations in the world.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our San Antonio's climate page.
San Antonio Temperature in September
Min Temperature
21°C (70°F)
Max Temperature
33°C (91°F)
Chance of Rain
29%
Precipitation
102 mm (4 in)
Rainy days
9 days
Humidity
68%
Sunshine
235 hours
Percentage Sunshine
63%
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in San Antonio typically drop from around 34°C (93°F) at the start of September to approximately 31°C (88°F) by the end. Nights are warm, with lows typically ranging from 18°C (64°F) to 24°C (75°F).
Average temperatures in September
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in September
Historical weather for San Antonio in September
Browse day-by-day weather records for San Antonio spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
San Antonio historical weather extremes in September
The extremes listed below come from historical weather data collected in San Antonio from 1976 through 2025.
- The hottest September day on record in San Antonio reached 43°C (109°F) (September 5, 2000).
- The coldest night in September in San Antonio was on September 19, 1981, with a minimum of 8°C (46°F).
Best Places in the United States of America in September
Find out more about the weather in the United States of America and which places have the best travel conditions in this month. See all of the United States of America in September →
perfect weather
pleasant
tolerable
unpleasant
poor
What to Wear in San Antonio in September
Warm temperatures in September make for comfortable sightseeing weather. Pack breathable fabrics like cotton shirts, knee-length shorts or skirts, and comfortable walking shoes. A thin long sleeve for indoor spaces is handy. Prepare for significant rainfall with proper waterproof clothing and shoes. And with plenty of sunshine hours, don’t forget sunglasses, sunscreen, and maybe a sun hat.What To Do in San Antonio in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our San Antonio's climate page.
Temperature Rainfall Sunshine Humidity
See the full San Antonio climate overview or explore weather in the United States of America.
