Piedras Negras weather in September

In September, Piedras Negras sees average daytime highs of 34°C and overnight lows near 23°C, with 79 mm of rain across 8.3 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 35°C in the first days to 32°C by the end. The sky is clear or mostly clear about 53% of the time in September, and the air most often feels muggy.

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 Piedras Negras's 5th-clearest and 9th-windiest month. For the whole year in context, see Piedras Negras's year-round climate.

Daytime high
34°
4th warmest
Overnight low
23°
9th coldest
Rainfall
79 mm
8.3 wet days
Daylight
12 h 12 min
6:31 AM – 6:41 PM
Cloud cover
43%
5th clearest
Wind
12 km/h
9th windiest
Solar energy
5.35 kWh/m²
Travel score
3.5
out of 10

Piedras Negras is municipal seat of Piedras Negras, State of Coahuila, Mexico.

Founded
1850

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 35°C in the first days to 32°C by the end.

A typical September day in Piedras Negras reaches about 34°C in the afternoon and slips back to 23°C overnight — a 11°C spread between the day's warmth and the night's chill. On most days the high lands between 29°C and 38°C. Set against its neighbours, September runs about 4°C cooler than August and about 5°C warmer than October.

15°20°25°30°35°40°151015202530
Avg high (°C)Avg low (°C)
13625
23525
33525
43525
53524
63524
73524
83424
93424
103424
113424
123424
133423
143423
153423
163323
173323
183323
193323
203322
213322
223322
233322
243322
253322
263321
273221
283221
293221
303221

How September really feels in Piedras Negras

Once humidity and wind are folded in, September averages 30 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
30
heat index over the day's high
Days feeling ≤ C
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.

Piedras Negras 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 (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan19° / 254.410.47.1
Feb22° / 10°274.5117.6
Mar26° / 14°435.611.87.5
Apr30° / 18°486.112.75.5
May33° / 22°748.313.43.5
Jun36° / 25°466.113.82.1
Jul37° / 26°505.913.61.6
Aug37° / 26°464.6131.6
Sep34° / 23°798.312.23.5
Oct29° / 18°606.511.36.2
Nov23° / 12°364.810.67.8
Dec19° / 274.510.27.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 53% 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 29%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
17129
27129
37030
47030
57030
66832
76832
86832
96733
106832
116832
126832
136832
146931
156931
166931
177030
187030
197030
207228
217228
227327
237426
247525
257525
267525
277624
287723
297723
307723

Chance of precipitation in September

Any precipitation

Piedras Negras gets around 79 mm of rain over 8.3 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 27% and peaks near 32% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%40%151015202530
Rain chance (%)
126
227
328
429
530
631
731
832
932
1032
1132
1231
1331
1430
1530
1629
1728
1827
1926
2025
2124
2224
2323
2422
2522
2621
2721
2821
2921
3022

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the muggy band about 36% of days. Sticky, muggy-or-worse air turns up on roughly 66% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1241743341
2341641350
3341640360
4441639370
5441539370
6441538380
7541538380
8541538380
9541438380
10651438370
11651438370
12651438360
13751438350
14761438341
15771538331
16871537321
17981537301
18991636291
1910101636281
2011111635271
2112121634261
2213121633251
2314131732231
2415141731221
2516141730211
2617151829211
2718151829201
2819151828191
2920151828180
3020151828180

Wind in September

Winds average 12 km/h in September.

Across September, daily wind ranges from about 12 km/h on the calmest days to 13 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
113light breeze
213light breeze
313light breeze
413light breeze
513light breeze
613light breeze
713light breeze
813light breeze
913light breeze
1013light breeze
1112light breeze
1212light breeze
1312light breeze
1412light breeze
1512light breeze
1612light breeze
1712light breeze
1812light breeze
1912light breeze
2012light breeze
2112light breeze
2212light breeze
2312light breeze
2412light breeze
2512light breeze
2612light breeze
2712light breeze
2812light breeze
2912light breeze
3012light breeze

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 6:24 AM to 6:39 AM, and sunset from 7:00 PM to 6:24 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.66:247:00
212.66:246:59
312.56:256:58
412.56:256:56
512.56:266:55
612.56:266:54
712.46:276:53
812.46:276:51
912.46:286:50
1012.36:286:49
1112.36:296:48
1212.36:296:46
1312.36:306:45
1412.26:306:44
1512.26:316:43
1612.26:316:41
1712.16:326:40
1812.16:326:39
1912.16:336:38
2012.16:336:36
2112.06:346:35
2212.06:346:34
2312.06:356:33
2411.96:356:31
2511.96:366:30
2611.96:376:29
2711.86:376:28
2811.86:386:27
2911.86:386:25
3011.86:396:24

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.35 kWh/m².

For context, solar energy here swings from a low near 3.04 kWh/m² to a high of 6.86 kWh/m² in July across the year — September's 5.35 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.9Bright
25.8Bright
35.8Bright
45.7Bright
55.7Bright
65.6Bright
75.6Bright
85.5Bright
95.5Bright
105.4Bright
115.4Bright
125.4Bright
135.3Bright
145.3Bright
155.3Bright
165.3Bright
175.3Bright
185.3Bright
195.3Bright
205.2Bright
215.2Bright
225.2Bright
235.2Bright
245.2Bright
255.2Bright
265.2Bright
275.1Bright
285.1Bright
295.1Bright
305.0Bright
Planning a trip in September

Is September a good time to visit Piedras Negras?

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

3.5
Sightseeing
8th-best month of the year
6.4
Beach & pool
5th-best month of the year

September is a weaker month for outdoor sightseeing in Piedras Negras. The water and warmth also suit a beach or pool day.

What to pack for Piedras Negras in September

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

In September, Piedras Negras sees daytime highs around 34°C and nights near 23°C. Pack light clothes. Worth having: rain gear and sun protection. About 8 days see rain.

light clothesrain gearsun protection

UV index in Piedras Negras 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 Piedras Negras peaks around July 14 at about 11 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 18 at about 4 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecHighVery highExtremeVery highHighModerateJul 14UV 11Dec 18UV 4
UV index (midday)Level
Jan5Moderate
Feb6High
Mar7Very high
Apr10Very high
May10Extreme
Jun11Extreme
Jul11Extreme
Aug11Extreme
Sep9Very high
Oct7High
Nov5Moderate
Dec4Moderate

Air quality in Piedras Negras 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 Piedras Negras is worst in July — around 18 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (February, 8 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1418 µg/m³Feb 178 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb8Good
Mar9Good
Apr10Good
May16Moderate
Jun16Moderate
Jul18Moderate
Aug13Moderate
Sep12Good
Oct9Good
Nov10Good
Dec11Good
Location & terrain

Where is Piedras Negras?

Piedras Negras sits at 28.7°N, 100.5°W, 223 m above sea level, in Mexico. The nearest listed city is Eagle Pass, 3.0 km away.

Topography around Piedras Negras

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Piedras Negras.

Within 3 km, the terrain around Piedras Negras has only modest variations in elevation — a maximum elevation change of 52 m around an average of 227 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 110 m; within 80 km, significant variations in elevation — a maximum elevation change of 586 m.

The land around Piedras Negras is covered by artificial surfaces (60%) within 3 km, shrubs (70%) within 16 km, and shrubs (89%) within 80 km.

3 km
52 m
16 km
110 m
80 km
586 m
treesshrubsgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Eagle Pass 3.0 km · Nava 39 km · Allende 51 km · Ciudad Acuña 81 km · Del Rio 82 km · Uvalde 91 km · Nueva Rosita 109 km · Sabinas 110 km

Mexico travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type A / B
120 / 127 V · 60 Hz
Prices
≈ 54% of US
price level, 2025
GDP per capita
$13,889
2025
Happiness
7.0 / 10
World Happiness, 2025
Safe drinking water
43%
of population, 2024
Homicide rate
24.9
per 100k, 2023
Road deaths
12.8
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Very low
EF EPI 440
Religion
Catholic 78%no religion 11%other Evangelical Churches 8%Jehovah Witness 1%

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 Piedras Negras (28.7001°, -100.5235°, elevation 223 m), 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).