San Antonio weather in September: San Antonio, Texas: normal highs, lows, rain and records for September
San Antonio in September has a normal high of 90°F and a normal low of 70°F, a daily mean of 80°F, falling from 94°F on the 1st to 87°F by the 30th. Measurable precipitation falls on 7 days in a normal September, 3.88 inches in all. (NOAA 1991-2020 normals)
In metric: a normal high of 32°C and low of 21°C, 99 mm of precipitation in September.
- NOAA stationSan Antonio International Airport
- Station IDUSW00012921
- Location29.54°N 98.48°W
- Elevation789 ft (241 m)
- From the center6 miles
- Population1,526,656
- Jan 63° 41°
- Feb 68° 45°
- Mar 74° 52°
- Apr 80° 58°
- May 87° 66°
- Jun 92° 73°
- Jul 95° 75°
- Aug 96° 75°
- Sep 90° 70°
- Oct 82° 60°
- Nov 72° 50°
- Dec 65° 42°
Each month: normal high (large) and low, °F. Fill: the month's normal mean, colder blue to hotter red.
How warm is San Antonio in September?
The normal high is 90°F and the normal low 70°F, for a daily mean of 79.9°F. September is 5.6°F cooler than August and 8.6°F warmer than October. September is the 4th warmest month of the year in San Antonio and the 2nd wettest. Across the month the normal high falls 7°F, from 94°F on September 1 to 87°F on September 30. From one year to the next September's mean temperature typically moves about 2.2°F either way (NOAA's standard deviation), so roughly two Septembers in three average between 78°F and 82°F.
Bars above: each day's normal high to low. Columns below: the chance of 0.01 inch or more of precipitation that day, on a scale of 0 to 100% (highest 23%).
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in |
|---|---|---|---|---|
| September 1 | 94°F | 73°F | 21% | 15% |
| September 8 | 92°F | 72°F | 22% | 16% |
| September 15 | 90°F | 70°F | 23% | 16% |
| September 22 | 89°F | 68°F | 22% | 15% |
| September 30 | 87°F | 66°F | 21% | 13% |
Every day of September: normal high, low and chance of precipitation (warmest afternoon September 1, coldest night September 30)
| Day | High | Low | Chance of 0.01 in | Chance of 0.10 in | Daylight |
|---|---|---|---|---|---|
| September 1 | 94°F | 73°F | 21% | 15% | 12 h 50 min |
| September 2 | 93°F | 73°F | 21% | 15% | 12 h 50 min |
| September 3 | 93°F | 73°F | 22% | 15% | 12 h 40 min |
| September 4 | 93°F | 73°F | 22% | 15% | 12 h 40 min |
| September 5 | 93°F | 72°F | 22% | 15% | 12 h 40 min |
| September 6 | 92°F | 72°F | 22% | 15% | 12 h 40 min |
| September 7 | 92°F | 72°F | 22% | 16% | 12 h 40 min |
| September 8 | 92°F | 72°F | 22% | 16% | 12 h 40 min |
| September 9 | 92°F | 71°F | 23% | 16% | 12 h 30 min |
| September 10 | 91°F | 71°F | 23% | 16% | 12 h 30 min |
| September 11 | 91°F | 71°F | 23% | 16% | 12 h 30 min |
| September 12 | 91°F | 71°F | 23% | 16% | 12 h 30 min |
| September 13 | 91°F | 70°F | 23% | 16% | 12 h 30 min |
| September 14 | 90°F | 70°F | 23% | 16% | 12 h 20 min |
| September 15 | 90°F | 70°F | 23% | 16% | 12 h 20 min |
| September 16 | 90°F | 70°F | 23% | 16% | 12 h 20 min |
| September 17 | 90°F | 69°F | 22% | 15% | 12 h 20 min |
| September 18 | 90°F | 69°F | 22% | 15% | 12 h 20 min |
| September 19 | 89°F | 69°F | 22% | 15% | 12 h 20 min |
| September 20 | 89°F | 69°F | 22% | 15% | 12 h 10 min |
| September 21 | 89°F | 68°F | 22% | 15% | 12 h 10 min |
| September 22 | 89°F | 68°F | 22% | 15% | 12 h 10 min |
| September 23 | 88°F | 68°F | 22% | 15% | 12 h 10 min |
| September 24 | 88°F | 67°F | 21% | 14% | 12 h 10 min |
| September 25 | 88°F | 67°F | 21% | 14% | 12 h 10 min |
| September 26 | 88°F | 67°F | 21% | 14% | 12 h |
| September 27 | 88°F | 67°F | 21% | 14% | 12 h |
| September 28 | 87°F | 66°F | 21% | 14% | 12 h |
| September 29 | 87°F | 66°F | 21% | 14% | 12 h |
| September 30 | 87°F | 66°F | 21% | 13% | 12 h |
- Normal high
- 90°FSeptember average
- Normal low
- 70°FSeptember average
- Precipitation
- 3.88 inmonth total
- Days with precipitation
- 70.01 inch or more
- Days at 90°F or more
- 20
- Daylight
- 12 h 50 min to 12 hSeptember 1 to September 30
- Days at 70°F or more
- 30
- Days at 80°F or more
- 28
- Sunshine
- 81%of clear-sky sunlight (NASA)
Source: NOAA NCEI 1991-2020 daily normals, station USW00012921; monthly normals. Daylight is computed from the place's latitude with NOAA's solar equations.
Does it rain in San Antonio in September?
On a given September day the chance of 0.01 inch or more is 22% on average, highest around September 11 (23%). In all, 3.88 in falls on 7 days of a normal September, 1 of them with an inch or more.
In a normal September in San Antonio, 20 days reach 90°F.
Source: NOAA NCEI 1991-2020 daily and monthly normals, station USW00012921.
How humid and windy is San Antonio in September?
At 3 p.m. the normal temperature is 86°F with 41% relative humidity and a dew point of 60°F; at 6 a.m. it is 67°F with 83% humidity. The wind averages 7.1 mph, most often from the east-southeast in the afternoon.
| Time | Temperature | Dew point | Humidity | Wind | Clear or few clouds |
|---|---|---|---|---|---|
| 6 a.m. | 67°F | 62°F | 83% | 5.1 mph | 43% |
| 9 a.m. | 75°F | 64°F | 68% | 7.4 mph | 38% |
| noon | 83°F | 62°F | 49% | 8.4 mph | 40% |
| 3 p.m. | 86°F | 60°F | 41% | 8.7 mph | 45% |
| 6 p.m. | 82°F | 59°F | 46% | 9.0 mph | 55% |
| 9 p.m. | 75°F | 61°F | 62% | 7.3 mph | 62% |
Source: NOAA NCEI 1991-2020 hourly normals, station USW00012921. Hourly normals exist only for NOAA's first-order stations; a dash where NOAA publishes no value for that hour (the sky at some hours).
What are the records for September in San Antonio?
The warmest September temperature on San Antonio's official record (since 1885) is 111°F, on September 5, 2000; the coldest is 41°F, on September 27, 1942. The wettest September brought 16.86 in (2018).
The September mean against the 1991-2020 normal of 79.9°F: 2021 82.1°F (+2.2), 2022 82.5°F (+2.6), 2023 87.0°F (+7.1), 2024 83.3°F (+3.4), 2025 81.7°F (+1.8), 2026 87.0°F (+7.1). 6 of 6 ran warmer than normal.
| September | Mean | Against normal | Precip. |
|---|---|---|---|
| 2021 | 82.1°F | +2.2°F | 2.59 in |
| 2022 | 82.5°F | +2.6°F | 0.98 in |
| 2023 | 87.0°F | +7.1°F | 0.43 in |
| 2024 | 83.3°F | +3.4°F | 1.46 in |
| 2025 | 81.7°F | +1.8°F | 1.29 in |
| 2026 | 87.0°F | +7.1°F | 0.48 in |
Source: records: ACIS, NWS threaded record SATthr; recent months: ACIS, station USW00012921. Records and recent months use complete months only.
How does September in San Antonio compare across Texas?
Across the 321 places PlainClimate covers in Texas, September normal highs run from 81°F in Hart to 95°F in Presidio; San Antonio's is 90°F.
Source: NOAA NCEI 1991-2020 monthly normals for every station in the state.