Mercedes weather in September

In September, Mercedes sees average daytime highs of 92°F and overnight lows near 75°F, with 3.6 in of rain across 13 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 94°F in the first days to 90°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 Mercedes's 8th-clearest and 12th-windiest month. For the whole year in context, see Mercedes's year-round climate.

Daytime high
92°
4th warmest
Overnight low
75°
9th coldest
Rainfall
3.6 in
13 wet days
Daylight
12 h 12 min
6:21 AM – 6:31 PM
Cloud cover
53%
8th clearest
Wind
8 mph
12th windiest
Solar energy
5.22 kWh/m²
Travel score
3.2
out of 10

Mercedes is city in Texas, USA.

Density
559/km²
people per km²
Founded
1907

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 94°F in the first days to 90°F by the end.

A typical September day in Mercedes reaches about 92°F in the afternoon and slips back to 75°F overnight — a 17°F spread between the day's warmth and the night's chill. On most days the high lands between 86°F and 98°F. Set against its neighbours, September runs about 5°F cooler than August and about 5°F warmer than October.

60°70°80°90°100°151015202530
Avg high (°F)Avg low (°F)
19477
29477
39477
49477
59476
69376
79376
89376
99376
109276
119276
129275
139275
149275
159275
169275
179175
189174
199174
209174
219174
229174
239173
249173
259173
269073
279072
289072
299072
309072

How September really feels in Mercedes

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
9 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.

Mercedes 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
Jan72° / 53°1.14.810.57.4
Feb76° / 56°1.04.811.17.7
Mar81° / 62°1.55.511.87.0
Apr87° / 68°1.75.512.65.3
May91° / 73°2.16.913.33.8
Jun95° / 77°2.17.713.62.7
Jul97° / 78°2.2713.52.3
Aug97° / 78°1.77.712.92.1
Sep92° / 75°3.61312.23.2
Oct87° / 68°2.57.211.45.3
Nov79° / 60°1.56.210.77.4
Dec73° / 54°1.35.410.47.5

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 19% of September, with mostly cloudy or overcast conditions the remaining 40%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15842
25644
35644
45545
55644
65545
75545
85545
95545
105545
115644
125644
135644
145743
155743
165842
175842
185941
196040
206139
216238
226436
236535
246733
256733
266832
277030
287030
297030
307129

Chance of precipitation in September

Any precipitation

Mercedes gets around 3.6 in of rain over 13 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 42% and peaks near 50% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
142
243
345
446
548
649
750
850
950
1050
1150
1249
1348
1447
1546
1645
1744
1842
1941
2040
2138
2237
2336
2434
2533
2633
2732
2831
2931
3030

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 55% of days. Sticky, muggy-or-worse air turns up on roughly 91% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
100176824
201176625
301186426
401186426
501286227
601286227
701286128
801286128
901286029
1001385929
1101385830
1201385830
1301395730
1401495630
1502495629
16025105429
17126105328
18126115327
19137125126
20138135025
21138135123
22249144922
232410154820
242511164719
252511174618
262512184616
273612194515
283613204414
293613204413
303714214313

Wind in September

Winds average 8 mph in September, the calmest month.

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

051015151015202530
Wind speed (mph)Feels
18light breeze
28light breeze
38light breeze
48light breeze
58light breeze
68light breeze
78light breeze
88light breeze
98light breeze
108light breeze
118light breeze
128light breeze
138light breeze
148light breeze
158light breeze
168light breeze
178light breeze
188light breeze
198light breeze
208light breeze
218light breeze
228light breeze
238light breeze
248light breeze
258light breeze
268light breeze
278light breeze
288light breeze
298light breeze
308light 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 6:15 AM to 6:27 AM, and sunset from 6:48 PM to 6:14 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.56:156:48
212.56:166:46
312.56:166:45
412.56:166:44
512.46:176:43
612.46:176:42
712.46:186:41
812.46:186:40
912.36:196:39
1012.36:196:37
1112.36:196:36
1212.36:206:35
1312.26:206:34
1412.26:216:33
1512.26:216:32
1612.26:216:31
1712.16:226:29
1812.16:226:28
1912.16:236:27
2012.06:236:26
2112.06:246:25
2212.06:246:24
2312.06:246:22
2411.96:256:21
2511.96:256:20
2611.96:266:19
2711.96:266:18
2811.86:276:17
2911.86:276:16
3011.86:276:14

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.22 kWh/m².

For context, solar energy here swings from a low near 2.99 kWh/m² to a high of 6.73 kWh/m² in July across the year — September's 5.22 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.7Bright
25.6Bright
35.6Bright
45.5Bright
55.5Bright
65.5Bright
75.4Bright
85.4Bright
95.3Bright
105.3Bright
115.3Bright
125.3Bright
135.2Bright
145.2Bright
155.2Bright
165.2Bright
175.2Bright
185.2Bright
195.1Bright
205.1Bright
215.1Bright
225.1Bright
235.1Bright
245.1Bright
255.1Bright
265.1Bright
275.1Bright
285.1Bright
295.0Bright
305.0Bright
Planning a trip in September

Is September a good time to visit Mercedes?

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

3.2
Sightseeing
9th-best month of the year
5.8
Beach & pool
7th-best month of the year

September is a weaker month for outdoor sightseeing in Mercedes.

What to pack for Mercedes in September

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

In September, Mercedes sees daytime highs around 92°F and nights near 75°F. Pack light clothes. Worth having: rain gear and sun protection. About 13 days see rain.

light clothesrain gearsun protection

UV index in Mercedes 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 Mercedes 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 Mercedes 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 Mercedes is worst in July — around 26 µg/m³ PM2.5 (moderate), about 3.5× the cleanest month (November, 7 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1625 µg/m³Nov 107 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb10Good
Mar11Good
Apr13Moderate
May20Moderate
Jun21Moderate
Jul26Moderate
Aug19Moderate
Sep12Moderate
Oct8Good
Nov7Good
Dec9Good
Location & terrain

Where is Mercedes?

Mercedes sits at 26.1°N, 97.9°W, 69 ft above sea level, in United States. The nearest listed city is Weslaco, 5.0 mi away.

Topography around Mercedes

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

Within 2 miles, the terrain around Mercedes has only modest variations in elevation — a maximum elevation change of 39 ft around an average of 66 ft above sea level; within 10 miles, only modest variations in elevation — a maximum elevation change of 174 ft; within 50 miles, only modest variations in elevation — a maximum elevation change of 617 ft.

The land around Mercedes is covered by grassland (31%), cropland (26%) and trees (20%) within 2 miles, cropland (52%) and grassland (20%) within 10 miles, and cropland (40%) and grassland (24%) within 50 miles.

2 miles
39 ft
10 miles
174 ft
50 miles
617 ft
treesshrubsgrasslandcroplandartificial surfacesbare terrainwaterwetland
September weather nearby: Weslaco 5.0 mi · Donna 8.7 mi · Alamo 13 mi · Harlingen 14 mi · San Juan 16 mi · Ciudad Río Bravo 16 mi · Pharr 17 mi · San Benito 17 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 Mercedes (26.1498°, -97.9136°, elevation 69 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).