San Antonio weather in September

In September, San Antonio sees average daytime highs of 89°F and overnight lows near 70°F, with 3.0 in of rain across 8.6 wet days and about 12.2 hours of daylight. It is the 4th-warmest and 5th-wettest month of the year here.

Highs ease over the month, from about 92°F in the first days to 87°F by the end. The sky is clear or mostly clear about 50% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 36 min at the start of September to 11 h 48 min by month's end. Set against the rest of the year, September is San Antonio's 4th-clearest and 12th-windiest month. For the whole year in context, see San Antonio's year-round climate.

Daytime high
89°
4th warmest
Overnight low
70°
9th coldest
Rainfall
3.0 in
8.6 wet days
Daylight
12 h 12 min
6:23 AM – 6:34 PM
Cloud cover
46%
4th clearest
Wind
6 mph
12th windiest
Solar energy
5.2 kWh/m²
Travel score
4.3
out of 10

San Antonio is city in Bexar, Comal, and Medina counties in Texas, United States; seat of Bexar County.

Density
1,263/km²
people per km²
Founded
1718

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 92°F in the first days to 87°F by the end.

A typical September day in San Antonio reaches about 89°F in the afternoon and slips back to 70°F overnight — a 19°F spread between the day's warmth and the night's chill. On most days the high lands between 82°F and 96°F. Set against its neighbours, September runs about 6°F cooler than August and about 8°F warmer than October.

60°80°100°151015202530
Avg high (°F)Avg low (°F)
19373
29273
39273
49273
59272
69172
79172
89172
99172
109071
119071
129071
139071
148971
158970
168970
178970
188969
198969
208869
218869
228868
238868
248868
258767
268767
278767
288766
298766
308666

How September really feels in San Antonio

Once humidity and wind are folded in, September averages 21 days that feel above 90°F and 0 that feel at or below 32°F — the comfort signal a plain temperature reading hides.

Days feeling ≥ 90°F
21
heat index over the day's high
Days feeling ≤ 32°F
0
wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

San Antonio weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 5th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan62° / 43°2.27.210.35.8
Feb67° / 46°2.37.410.96.5
Mar73° / 53°3.19.211.86.9
Apr80° / 59°3.18.512.76.8
May86° / 67°4.111.213.55.0
Jun91° / 73°2.79.513.83.6
Jul94° / 74°2.06.213.73.1
Aug95° / 74°1.95.813.12.8
Sep89° / 70°3.08.612.24.3
Oct81° / 61°3.37.711.36.8
Nov71° / 51°2.67.210.57.1
Dec64° / 44°2.57.510.16.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 50% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 33%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16931
26931
36832
46733
56634
66634
76436
86436
96436
106337
116337
126337
136238
146337
156337
166337
176436
186535
196535
206634
216832
226931
237030
247129
257327
267327
277426
287426
297525
307426

Chance of precipitation in September

Any precipitation

San Antonio gets around 3.0 in of rain over 8.6 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 29% and peaks near 33% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%151015202530
Rain chance (%)
130
230
331
432
532
633
733
833
933
1033
1133
1233
1333
1432
1532
1631
1730
1829
1928
2028
2127
2226
2325
2424
2524
2623
2723
2822
2922
3022

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels oppressive — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the oppressive band about 35% of days. Sticky, muggy-or-worse air turns up on roughly 67% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1251240391
2261240391
3361239391
4361239391
5361239391
6371238391
7471238391
8471237391
9471237401
10571236401
11571235400
12571135410
13681234410
14681233410
15791232400
16791331400
17891430390
189101429380
1910101528370
2011101627350
2113101726340
2214111725320
2316111824310
2417111924290
2518111923280
2620111923260
2721122023240
2822122023230
2923122023220
3024122023200

Wind in September

Winds average 6 mph in September, the calmest month.

Across September, daily wind ranges from about 6 mph on the calmest days to 6 mph at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (mph)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 36 min at the start of September to 11 h 48 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 48 minutes over September. Sunrise moves from 6:15 AM to 6:31 AM, and sunset from 6:52 PM to 6:16 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.66:156:52
212.66:166:51
312.66:166:50
412.56:176:49
512.56:176:47
612.56:186:46
712.46:186:45
812.46:196:44
912.46:196:42
1012.46:206:41
1112.36:206:40
1212.36:216:39
1312.36:216:37
1412.26:226:36
1512.26:236:35
1612.26:236:34
1712.16:246:32
1812.16:246:31
1912.16:256:30
2012.16:256:28
2112.06:266:27
2212.06:266:26
2312.06:276:25
2411.96:276:23
2511.96:286:22
2611.96:296:21
2711.86:296:20
2811.86:306:18
2911.86:306:17
3011.86:316:16

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.2 kWh/m².

For context, solar energy here swings from a low near 2.72 kWh/m² to a high of 6.71 kWh/m² in July across the year — September's 5.2 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.7Bright
25.6Bright
35.6Bright
45.5Bright
55.5Bright
65.4Bright
75.4Bright
85.3Bright
95.3Bright
105.3Bright
115.2Bright
125.2Bright
135.2Bright
145.1Bright
155.1Bright
165.1Bright
175.1Bright
185.1Bright
195.1Bright
205.1Bright
215.1Bright
225.1Bright
235.1Bright
245.0Bright
255.0Bright
265.0Bright
275.0Bright
285.0Bright
295.0Bright
304.9Bright
Planning a trip in September

Is September a good time to visit San Antonio?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

4.3
Sightseeing
9th-best month of the year
6.8
Beach & pool
2nd-best month of the year

September is a reasonable time to visit San Antonio for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for San Antonio in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, San Antonio sees daytime highs around 89°F and nights near 70°F. Pack light clothes. Worth having: rain gear and sun protection. About 9 days see rain.

light clothesrain gearsun protection

UV index in San Antonio in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 9 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in San Antonio peaks around August 11 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 20 at about 4 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highHighModerateAug 11UV 11Dec 20UV 4
UV index (midday)Level
Jan4Moderate
Feb6High
Mar7Very high
Apr10Very high
May10Extreme
Jun11Extreme
Jul11Extreme
Aug11Extreme
Sep9Very high
Oct6High
Nov5High
Dec4Moderate

Air quality in San Antonio in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in San Antonio is worst in July — around 18 µg/m³ PM2.5 (moderate), about 2.8× the cleanest month (October, 6 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1317 µg/m³Oct 246 µg/m³
PM2.5 (µg/m³)Level
Jan7Good
Feb7Good
Mar9Good
Apr10Good
May15Moderate
Jun15Moderate
Jul18Moderate
Aug12Good
Sep10Good
Oct6Good
Nov6Good
Dec7Good
Location & terrain

Where is San Antonio?

San Antonio sits at 29.4°N, 98.5°W, 650 ft above sea level, in United States. The nearest listed city is Converse, 12 mi away.

Topography around San Antonio

How much the land rises and falls, and what covers it, within 2, 10 and 50 miles of San Antonio.

Within 2 miles, the terrain around San Antonio has only modest variations in elevation — a maximum elevation change of 174 ft around an average of 669 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 607 ft; within 50 miles, significant variations in elevation — a maximum elevation change of 1,827 ft.

The land around San Antonio is covered by artificial surfaces (75%) within 2 miles, trees (38%), artificial surfaces (38%) and grassland (20%) within 10 miles, and trees (50%) and grassland (38%) within 50 miles.

2 miles
174 ft
10 miles
607 ft
50 miles
1,827 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrain
September weather nearby: Converse 12 mi · Live Oak 14 mi · Universal City 15 mi · Schertz 16 mi · Cibolo 19 mi · New Braunfels 29 mi · Seguin 34 mi · Canyon Lake 34 mi

United States travel facts

Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 100% of US
price level, 2025
GDP per capita
$90,027
2025
Happiness
6.8 / 10
World Happiness, 2025
Safe drinking water
98%
of population, 2024
Homicide rate
5.8
per 100k, 2023
Road deaths
12.7
per 100k/yr, 2019
Income group
High
World Bank
Religion
Protestant 47%unaffiliated 23%Roman Catholic 21%Jewish 2%

Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.

Data sources

Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for San Antonio (29.4241°, -98.4936°, elevation 650 ft), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).