Retalhuleu weather in September

In September, Retalhuleu sees average daytime highs of 30°C and overnight lows near 23°C, with 456 mm of rain across 29.2 wet days and about 12.1 hours of daylight. It is the 11th-warmest and 1st-wettest month of the year here.

Day-to-day highs hold fairly steady near 30°C through the month. The sky is clear or mostly clear about 1% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 18 min at the start of September to 11 h 54 min by month's end. Set against the rest of the year, September is Retalhuleu's 12th-clearest and 7th-windiest month. For the whole year in context, see Retalhuleu's year-round climate.

Daytime high
30°
11th warmest
Overnight low
23°
7th coldest
Rainfall
456 mm
29.2 wet days
Daylight
12 h 06 min
5:59 AM – 6:03 PM
Cloud cover
86%
12th clearest
Wind
4 km/h
7th windiest
Solar energy
4.9 kWh/m²
Travel score
2.6
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 30°C through the month.

A typical September day in Retalhuleu reaches about 30°C in the afternoon and slips back to 23°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 28°C and 32°C. Set against its neighbours, September runs on par with August and on par with October.

20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
13023
23023
33023
43023
53023
63023
73023
83023
93023
103023
113023
123023
133023
143023
153023
163023
173023
183023
193023
203023
213023
223023
233023
243023
253023
263023
273023
283023
293023
303023

How September really feels in Retalhuleu

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.

Retalhuleu weather by month

How September compares with the rest of the year at a glance. September is the 11th-warmest and 1st-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan31° / 21°184.911.25.3
Feb32° / 22°153.811.54.8
Mar33° / 23°368.511.94.0
Apr33° / 23°9414.412.33.2
May32° / 24°3512712.72.6
Jun30° / 23°37428.412.82.6
Jul31° / 23°2872712.82.8
Aug30° / 23°36128.612.52.7
Sep30° / 23°45629.212.12.6
Oct30° / 23°38427.711.73.0
Nov30° / 23°11615.511.34.4
Dec31° / 22°276.111.25.4

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 1% of the time in September, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 6% of September, with mostly cloudy or overcast conditions the remaining 93%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
11090
21090
3991
4991
5991
6793
7793
8793
9793
10793
11793
12793
13793
14793
15694
16694
17694
18694
19694
20694
21694
22694
23694
24694
25694
26793
27892
28892
29991
30991

Chance of precipitation in September

Any precipitation

Retalhuleu gets around 456 mm of rain over 29.2 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 97% and peaks near 99% on the wettest days.

0%20%40%60%80%100%151015202530
Rain chance (%)
196
296
396
496
596
696
796
896
996
1096
1196
1296
1396
1496
1597
1697
1797
1897
1998
2098
2198
2298
2398
2498
2599
2699
2798
2898
2998
3098

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 97% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Oppressive (%)Miserable (%)
1973
2982
3982
4982
5982
6982
7982
8982
9982
10973
11973
12973
13964
14964
15964
16964
17964
18964
19964
20964
21964
22964
23964
24964
25964
26955
27955
28955
29955
30955

Wind in September

Winds average 4 km/h in September.

Across September, daily wind ranges from about 4 km/h on the calmest days to 4 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
14calm
24calm
34calm
44calm
54calm
64calm
74calm
84calm
94calm
104calm
114calm
124calm
134calm
144calm
154calm
164calm
174calm
184calm
194calm
204calm
214calm
224calm
234calm
244calm
254calm
264calm
274calm
284calm
294calm
304calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 18 min at the start of September to 11 h 54 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 24 minutes over September. Sunrise moves from 5:58 AM to 5:59 AM, and sunset from 6:15 PM to 5:53 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.35:586:15
212.35:586:14
312.35:586:14
412.25:586:13
512.25:586:12
612.25:586:11
712.25:586:10
812.25:586:10
912.25:586:09
1012.25:586:08
1112.15:586:07
1212.15:586:07
1312.15:596:06
1412.15:596:05
1512.15:596:04
1612.15:596:03
1712.15:596:03
1812.15:596:02
1912.05:596:01
2012.05:596:00
2112.05:595:59
2212.05:595:59
2312.05:595:58
2412.05:595:57
2512.05:595:56
2611.95:595:56
2711.95:595:55
2811.95:595:54
2911.95:595:53
3011.95:595:53

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.9 kWh/m².

For context, solar energy here swings from a low near 4.61 kWh/m² to a high of 6.34 kWh/m² in April across the year — September's 4.9 kWh/m² sits near the bottom.

0246151015202530
Solar energy (kWh/m²)Level
15.3Bright
25.3Bright
35.2Bright
45.2Bright
55.2Bright
65.2Bright
75.2Bright
85.2Bright
95.1Bright
105.1Bright
115.1Bright
125.0Bright
135.0Bright
145.0Bright
155.0Bright
164.9Bright
174.9Bright
184.8Bright
194.8Bright
204.8Bright
214.7Bright
224.7Bright
234.7Bright
244.7Bright
254.6Bright
264.6Bright
274.6Bright
284.6Bright
294.5Bright
304.5Bright
Planning a trip in September

Hazard calendar for Retalhuleu

In seasonPeak

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

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

Retalhuleu's rainy season runs May–October, when most of the year's rain falls.

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

Is September a good time to visit Retalhuleu?

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

2.6
Sightseeing
10th-best month of the year
3.6
Beach & pool
12th-best month of the year

September is a weaker month for outdoor sightseeing in Retalhuleu.

What to pack for Retalhuleu in September

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

In September, Retalhuleu sees daytime highs around 30°C and nights near 23°C. Pack light clothes and rain gear. Worth having: sun protection. About 29 days see rain.

light clothesrain gearsun protection

Sea temperature near Retalhuleu in September

The nearest coast averages about 30°C 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 46 km away) is warmest in July at about 30°C and coldest in February near 29°C.

The water stays above 20°C all year — warm enough for a swim any month.

28°30°32°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan29Tropical
Feb29Tropical
Mar29Tropical
Apr29Tropical
May30Tropical
Jun30Tropical
Jul30Tropical
Aug30Tropical
Sep30Tropical
Oct29Tropical
Nov30Tropical
Dec29Tropical

UV index in Retalhuleu in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 11 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Retalhuleu peaks around March 21 at about 12 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 14 at about 8 (very high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecVery highExtremeVery highMar 21UV 12Dec 14UV 8
UV index (midday)Level
Jan9Very high
Feb11Extreme
Mar12Extreme
Apr12Extreme
May11Extreme
Jun12Extreme
Jul11Extreme
Aug11Extreme
Sep11Extreme
Oct10Extreme
Nov8Very high
Dec8Very high

Air quality in Retalhuleu 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 Retalhuleu is worst in December — around 45 µg/m³ PM2.5 (poor), about 1.6× the cleanest month (June, 28 µg/m³).

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

0204060JanFebMarAprMayJunJulAugSepOctNovDecPoorModeratePoorDec 2145 µg/m³Jun 2228 µg/m³
PM2.5 (µg/m³)Level
Jan44Poor
Feb45Poor
Mar41Poor
Apr44Poor
May40Poor
Jun28Moderate
Jul29Moderate
Aug29Moderate
Sep29Moderate
Oct30Moderate
Nov37Poor
Dec45Poor
Location & terrain

Where is Retalhuleu?

Retalhuleu sits at 14.5°N, 91.7°W, 241 m above sea level, in Guatemala. The nearest listed city is San Sebastián, 4.0 km away.

Topography around Retalhuleu

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

Within 3 km, the terrain around Retalhuleu has only modest variations in elevation — a maximum elevation change of 123 m around an average of 237 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 1,034 m; within 80 km, extreme variations in elevation — a maximum elevation change of 4,178 m.

The land around Retalhuleu is covered by trees (47%) and grassland (26%) within 3 km, trees (63%) and grassland (24%) within 16 km, and trees (51%) and water (22%) within 80 km.

3 km
123 m
16 km
1,034 m
80 km
4,178 m
treesgrasslandcroplandartificial surfaceswatermangroves
September weather nearby: San Sebastián 4.0 km · Nuevo San Carlos 7.0 km · El Asintal 9.0 km · San Felipe 13 km · El Palmar 17 km · San Francisco Zapotitlán 18 km · Mazatenango 19 km · Colomba 20 km

Guatemala travel facts

Travel advisory
Level 3
Reconsider Travel
Power plugs
Type A / B
120 V · 60 Hz
Prices
≈ 43% of US
price level, 2025
GDP per capita
$6,598
2025
Happiness
6.5 / 10
World Happiness, 2025
Safe drinking water
49%
of population, 2024
Homicide rate
23.4
per 100k, 2023
Road deaths
22.9
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Moderate
EF EPI 510
Religion
Evangelical 46%Roman Catholic 42%none 11%

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 Retalhuleu (14.5358°, -91.6785°, elevation 241 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. 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).