San Antonio, TX weather in September
Expect hot, oppressively humid weather with some rain in San Antonio in September, with highs near 90°F and lows near 70°F. Rain falls on about 7 days.
- Normal high
- 90°F
- Normal low
- 70°F
- Wet days
- 7
- 3.9 in total
- Muggy days
- 20
- dew point 65°F+
How September changes from start to finish
| September 1 | September 30 | |
|---|---|---|
| Normal high | 94°F | 87°F |
| Normal low | 73°F | 66°F |
| Chance of a wet day | 22% | 21% |
| Sunrise / sunset | 7:11 am / 7:56 pm | 7:26 am / 7:21 pm |
| Daylight | 12.8 h | 11.9 h |
Chance of a wet day: average for the first and last 7 days of the month. Times are local clock time (Central Time).
A typical September day
- 6 am72°Fdew point 68°F
- 9 am79°Fdew point 69°F
- Noon86°Fdew point 66°F
- 3 pm89°Fdew point 64°F
- 6 pm86°Fdew point 64°F
- 9 pm79°Fdew point 66°F
NOAA hourly normals (local standard time) from San Antonio Kelly AFB (6 mi away); average wind 7 mph.
What kind of days to expect
- Comfortable dayshigh 65-80°F and dew point under 60°F1 of 30
- Hot dayshigh 90°F or more20 of 30
- Muggy daysdaily mean dew point 65°F or more20 of 30
- Wet daysat least 0.01 in of rain or melted snow7 of 30
- Notable rainat least 0.10 in5 of 30
- Freezing nightslow 32°F or below0 of 30
Average days per September, counted from daily records for each year 1991-2020.
Rain in September
Normal precipitation is 3.9 in; a dry September brings about 1.5 in and a wet one about 5.3 in (25th and 75th percentiles). About 3 days bring half an inch or more, and about 1 an inch or more.
How September varies from year to year
- Warmest September, 1991-20202019: average high 97°F
- Coolest September2003: average high 86°F
- Wettest September2018: 16.9 in
- Driest September1999: 0.05 in
- Highest reading111°F (September 5, 2000)
- Lowest reading48°F (September 27, 2000)
From the station's daily records with NOAA quality flags removed; most recent date shown when a reading repeats.
September compared with August and October
| August | September | October | |
|---|---|---|---|
| Normal high | 96°F | 90°F | 82°F |
| Normal low | 75°F | 70°F | 60°F |
| Wet days | 5 | 7 | 6 |
| Comfortable days | 0 | 1 | 6 |
| Daylight | 13.2 h | 12.3 h | 11.4 h |
Highs change by -6°F from August and -8°F into October.
How San Antonio ranks in September
- Normal high48th warmest of 378 cities; 13th of 38 in Texas
- Wet days147th driest of 378
- Comfortable days294th most of 342
What to pack for San Antonio in September
- Light, breathable clothing – highs near 90°F and about 20 muggy days
Heating and cooling
September has 1 heating degree days and 447 cooling degree days (base 65°F), 10% of the year's total heating and cooling demand.
Questions
How hot is San Antonio in September?
The normal high is 90°F and the normal low is 70°F. From 1991 to 2020 the hottest September reading was 111°F (September 5, 2000).
Does it rain a lot in San Antonio in September?
About 7 days in September have at least 0.01 in of precipitation, and the normal total is 3.9 in. The wettest September in 1991-2020 was in 2018 (16.9 in); the driest was in 1999 (0.05 in).
Is September a good time to visit San Antonio?
September ranks 10th of 12 months on our comfort score for San Antonio (37 out of 100). It has about 1 comfortable day and about 20 days at 90°F or hotter. The best months are February, March and November.
Where the numbers come from
- Temperature, rain, snowfall, snow depth and frost dates: San Antonio Intl Airport (USW00012921), 8.3 mi N of the city center, 789 ft (140 ft higher than the city). NOAA normals and daily records, 1991-2020.
- Humidity and wind by hour: San Antonio Kelly AFB (USW00012909), 6.1 mi WSW of the city center, 682 ft . NOAA normals and daily records, 1991-2020.
- Daily humidity and wind: San Antonio International Airport (722530-12921), 8.3 mi N of the city center, 799 ft (150 ft higher than the city). Hourly observations, 1991-2020.
- Not available for this location: cloud cover (no station close enough or similar enough in elevation).