Brownsville weather in September

In September, Brownsville sees average daytime highs of 89°F and overnight lows near 75°F, with 4.2 in of rain across 15.6 wet days and about 12.2 hours of daylight. It is the 4th-warmest and 1st-wettest month of the year here.

Highs ease over the month, from about 91°F in the first days to 87°F by the end. The sky is clear or mostly clear about 41% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 30 min at the start of September to 11 h 48 min by month's end. Set against the rest of the year, September is Brownsville's 7th-clearest and 12th-windiest month. For the whole year in context, see Brownsville's year-round climate.

Daytime high
89°
4th warmest
Overnight low
75°
9th coldest
Rainfall
4.2 in
15.6 wet days
Daylight
12 h 12 min
6:20 AM – 6:29 PM
Cloud cover
53%
7th clearest
Wind
9 mph
12th windiest
Solar energy
5.16 kWh/m²
Travel score
3.7
out of 10

Brownsville is seat of Cameron County, Texas, United States.

Density
493/km²
people per km²
Founded
1849

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 91°F in the first days to 87°F by the end.

A typical September day in Brownsville reaches about 89°F in the afternoon and slips back to 75°F overnight — a 14°F spread between the day's warmth and the night's chill. On most days the high lands between 84°F and 93°F. Set against its neighbours, September runs about 4°F cooler than August and about 5°F warmer than October.

60°70°80°90°100°151015202530
Avg high (°F)Avg low (°F)
19177
29177
39177
49177
59177
69077
79077
89076
99076
109076
118976
128976
138976
148976
158976
168976
178975
188975
198975
208975
218875
228874
238874
248874
258874
268874
278873
288773
298773
308773

How September really feels in Brownsville

Once humidity and wind are folded in, September averages 30 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
30
1 feel dangerously hot (≥ 102°F)
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.

Brownsville weather by month

How September compares with the rest of the year at a glance. September is the 4th-warmest and 1st-wettest month here — the current month is highlighted below.

MonthHigh / Low (°F)Rainfall (inches)Wet daysDaylight (hours)Travel score
Jan71° / 55°1.35.710.67.1
Feb74° / 58°1.15.311.17.5
Mar78° / 63°1.55.711.87.4
Apr83° / 68°1.95.912.66.5
May87° / 74°1.8713.25.0
Jun91° / 77°2.310.313.63.8
Jul92° / 78°2.58.813.53.5
Aug93° / 78°2.110.412.93.2
Sep89° / 75°4.215.612.23.7
Oct84° / 69°2.89.411.45.8
Nov78° / 62°1.77.610.77.2
Dec72° / 56°1.35.910.47.3

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 41% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 41%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15743
25743
35644
45545
55644
65545
75545
85446
95446
105446
115545
125545
135545
145644
155545
165644
175743
185743
195842
205941
216040
226139
236238
246337
256436
266535
276535
286634
296733
306733

Chance of precipitation in September

Any precipitation

Brownsville gets around 4.2 in of rain over 15.6 wet days in September, the wettest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 51% and peaks near 59% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
151
253
354
455
556
657
758
859
959
1059
1159
1258
1358
1457
1556
1655
1754
1853
1951
2050
2148
2246
2345
2444
2543
2642
2741
2840
2939
3039

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 42% of days. Sticky, muggy-or-worse air turns up on roughly 93% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
100144947
200144947
300144846
400144846
500254747
600254747
700254647
800254548
900254448
1000264448
1100364349
1200364249
1300374248
1400374148
1500484147
1601484146
1701494145
1801594044
19016104043
20026104042
21127113940
22128123939
23139133836
241310133835
251310143833
261411153931
271411153929
281412163928
291512174026
301513174024

Wind in September

Winds average 9 mph in September, the calmest month.

Across September, daily wind ranges from about 8 mph on the calmest days to 9 mph at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (mph)Feels
19light breeze
29light breeze
39light breeze
49light breeze
59light breeze
69light breeze
78light breeze
88light breeze
98light breeze
108light breeze
118light breeze
128light breeze
138light breeze
148light breeze
158light breeze
169light breeze
179light breeze
189light breeze
199light breeze
209light breeze
219light breeze
229light breeze
239light breeze
249light breeze
259light breeze
269light breeze
279light breeze
289light breeze
299light breeze
309light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 30 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 42 minutes over September. Sunrise moves from 6:14 AM to 6:26 AM, and sunset from 6:46 PM to 6:13 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.56:146:46
212.56:146:45
312.56:146:44
412.56:156:42
512.46:156:41
612.46:166:40
712.46:166:39
812.46:176:38
912.36:176:37
1012.36:176:36
1112.36:186:35
1212.36:186:33
1312.26:196:32
1412.26:196:31
1512.26:196:30
1612.26:206:29
1712.16:206:28
1812.16:216:27
1912.16:216:25
2012.06:216:24
2112.06:226:23
2212.06:226:22
2312.06:236:21
2411.96:236:20
2511.96:246:18
2611.96:246:17
2711.96:246:16
2811.86:256:15
2911.86:256:14
3011.86:266:13

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.16 kWh/m².

For context, solar energy here swings from a low near 2.92 kWh/m² to a high of 6.72 kWh/m² in July across the year — September's 5.16 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.7Bright
25.6Bright
35.5Bright
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
215.0Bright
225.0Bright
235.0Bright
245.0Bright
255.0Bright
265.0Bright
275.0Bright
285.0Bright
295.0Bright
304.9Bright
Planning a trip in September

Hazard calendar for Brownsville

In seasonPeak

In September, Brownsville sits inside its atlantic hurricane season. The full year is below, with each hazard's peak months called out.

Brownsville sits in the Atlantic hurricane belt; the season peaks August–October.

Atlantic hurricane
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Brownsville?

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

3.7
Sightseeing
10th-best month of the year
5.8
Beach & pool
10th-best month of the year

September is a weaker month for outdoor sightseeing in Brownsville.

What to pack for Brownsville in September

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

In September, Brownsville sees daytime highs around 89°F and nights near 75°F. Pack light clothes and rain gear. Worth having: sun protection. About 16 days see rain.

light clothesrain gearsun protection

Sea temperature near Brownsville in September

The nearest coast averages about 84°F in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 23 mi away) is warmest in September at about 84°F and coldest in February near 66°F.

It's comfortable for a long swim from Mar 18 to Jan 2 — about 9.6 months when the water holds above 68°F.

70°80°JanFebMarAprMayJunJulAugSepOctNovDeccoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°F)Comfort
Jan66Cool
Feb66Cool
Mar68Cool
Apr72Refreshing
May78Warm
Jun82Warm
Jul82Tropical
Aug83Tropical
Sep84Tropical
Oct81Warm
Nov75Warm
Dec70Refreshing

UV index in Brownsville in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 10 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Brownsville peaks around June 21 at about 12 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 5 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecHighVery highExtremeVery highExtremeVery highHighJun 21UV 12Dec 22UV 5
UV index (midday)Level
Jan5Moderate
Feb7High
Mar8Very high
Apr11Extreme
May9Very high
Jun12Extreme
Jul11Extreme
Aug11Extreme
Sep10Very high
Oct8Very high
Nov6High
Dec5Moderate

Air quality in Brownsville 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 Brownsville is worst in July — around 25 µg/m³ PM2.5 (moderate), about 3.7× the cleanest month (October, 7 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1525 µg/m³Oct 247 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb9Good
Mar11Good
Apr13Moderate
May19Moderate
Jun20Moderate
Jul25Moderate
Aug18Moderate
Sep13Moderate
Oct7Good
Nov7Good
Dec9Good
Location & terrain

Where is Brownsville?

Brownsville sits at 25.9°N, 97.5°W, 33 ft above sea level, in United States. The nearest listed city is Heroica Matamoros, 1.9 mi away.

Topography around Brownsville

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

Within 2 miles, the terrain around Brownsville has only modest variations in elevation — a maximum elevation change of 49 ft around an average of 36 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 92 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 259 ft.

The land around Brownsville is covered by artificial surfaces (50%) and trees (33%) within 2 miles, cropland (28%), grassland (22%) and artificial surfaces (20%) within 10 miles, and cropland (37%) and water (34%) within 50 miles.

2 miles
49 ft
10 miles
92 ft
50 miles
259 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwaterwetland
September weather nearby: Heroica Matamoros 1.9 mi · San Benito 18 mi · Harlingen 24 mi · Valle Hermoso 25 mi · Mercedes 31 mi · Weslaco 35 mi · Ciudad Río Bravo 37 mi · Donna 39 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 Brownsville (25.9017°, -97.4975°, elevation 33 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. 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).