La Unión weather in September

In September, La Unión sees average daytime highs of 26°C and overnight lows near 18°C, with 567 mm of rain across 29.2 wet days and about 12 hours of daylight. It is the 6th-warmest and 5th-wettest month of the year here.

Day-to-day highs hold fairly steady near 26°C through the month. The sky is clear or mostly clear about 0% of the time in September, and the air most often feels muggy.

Daylight stretches from about 12 h 06 min at the start of September to 12 hours by month's end. Set against the rest of the year, September is La Unión's 7th-clearest and 3rd-windiest month. For the whole year in context, see La Unión's year-round climate.

Daytime high
26°
6th warmest
Overnight low
18°
1st coldest
Rainfall
567 mm
29.2 wet days
Daylight
12 hours
5:58 AM – 5:59 PM
Cloud cover
92%
7th clearest
Wind
3 km/h
3rd windiest
Solar energy
4.42 kWh/m²
Travel score
3.4
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 26°C through the month.

A typical September day in La Unión reaches about 26°C in the afternoon and slips back to 18°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 23°C and 28°C. Set against its neighbours, September runs on par with August and on par with October.

15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12618
22618
32618
42618
52618
62618
72618
82618
92618
102618
112618
122618
132618
142618
152618
162618
172618
182618
192618
202618
212618
222618
232618
242618
252618
262618
272618
282618
292618
302618

La Unión weather by month

How September compares with the rest of the year at a glance. September is the 6th-warmest and 5th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan26° / 18°34829.311.83.7
Feb26° / 18°38826.611.93.6
Mar26° / 18°50830123.5
Apr26° / 18°67029.512.13.4
May26° / 18°69730.712.23.3
Jun26° / 18°55229.712.33.4
Jul26° / 18°47530.212.23.4
Aug26° / 18°44930.112.13.4
Sep26° / 18°56729.2123.4
Oct25° / 18°60930.311.93.4
Nov25° / 18°58729.211.83.5
Dec26° / 18°43930.311.73.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 0% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 1% of September, with mostly cloudy or overcast conditions the remaining 99%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1298
2298
3298
4298
5298
6298
7298
8199
9199
10199
11199
12199
13199
14199
15199
16199
17199
18199
19199
20199
21199
22199
23199
24199
25199
26199
27199
28199
29199
30199

Chance of precipitation in September

Any precipitation

La Unión gets around 567 mm of rain over 29.2 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 97% and peaks near 98% on the wettest days.

0%20%40%60%80%100%151015202530
Rain chance (%)
196
296
396
496
596
696
797
897
997
1097
1197
1297
1397
1497
1598
1698
1798
1898
1998
2098
2198
2298
2398
2498
2598
2698
2798
2898
2998
3098

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 84% of days. Sticky, muggy-or-worse air turns up on roughly 84% of them.

0%25%50%75%100%151015202530
Humid (%)Muggy (%)
11684
21684
31684
41684
51684
61684
71684
81684
91684
101684
111684
121684
131684
141684
151684
161585
171585
181585
191585
201585
211585
221585
231585
241585
251585
261585
271585
281684
291684
301684

Wind in September

Winds average 3 km/h in September.

Across September, daily wind ranges from about 3 km/h on the calmest days to 3 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
13calm
23calm
33calm
43calm
53calm
63calm
73calm
83calm
93calm
103calm
113calm
123calm
133calm
143calm
153calm
163calm
173calm
183calm
193calm
203calm
213calm
223calm
233calm
243calm
253calm
263calm
273calm
283calm
293calm
303calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 06 min at the start of September to 12 hours by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 6 minutes over September. Sunrise moves from 6:02 AM to 5:55 AM, and sunset from 6:07 PM to 5:53 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.16:026:07
212.16:016:06
312.16:016:06
412.16:016:05
512.16:016:05
612.16:006:04
712.16:006:04
812.16:006:03
912.16:006:03
1012.05:596:02
1112.05:596:02
1212.05:596:01
1312.05:596:01
1412.05:586:00
1512.05:586:00
1612.05:585:59
1712.05:585:59
1812.05:585:58
1912.05:575:58
2012.05:575:57
2112.05:575:57
2212.05:575:56
2312.05:565:56
2412.05:565:56
2512.05:565:55
2612.05:565:55
2712.05:555:54
2812.05:555:54
2912.05:555:53
3012.05:555:53

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.42 kWh/m².

For context, solar energy here swings from a low near 3.49 kWh/m² to a high of 4.54 kWh/m² in August across the year — September's 4.42 kWh/m² sits near the top of that range.

024151015202530
Solar energy (kWh/m²)Level
14.5Bright
24.5Bright
34.5Bright
44.5Bright
54.5Bright
64.5Bright
74.5Bright
84.5Bright
94.5Bright
104.5Bright
114.5Bright
124.5Bright
134.4Bright
144.4Bright
154.4Bright
164.4Bright
174.4Bright
184.4Bright
194.4Bright
204.4Bright
214.3Bright
224.3Bright
234.3Bright
244.3Bright
254.3Bright
264.3Bright
274.3Bright
284.3Bright
294.3Bright
304.2Bright
Planning a trip in September

Is September a good time to visit La Unión?

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

3.4
Sightseeing
6th-best month of the year
3.3
Beach & pool
7th-best month of the year

September is a weaker month for outdoor sightseeing in La Unión.

What to pack for La Unión in September

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

In September, La Unión sees daytime highs around 26°C and nights near 18°C. Pack rain gear. Worth having: light clothes. About 29 days see rain.

rain gearlight clothes

UV index in La Unión in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 14 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in La Unión peaks around February 19 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 13 at about 11 (extreme).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeFeb 19UV 15Dec 13UV 11
UV index (midday)Level
Jan13Extreme
Feb15Extreme
Mar15Extreme
Apr11Extreme
May14Extreme
Jun12Extreme
Jul13Extreme
Aug12Extreme
Sep14Extreme
Oct14Extreme
Nov12Extreme
Dec11Extreme

Air quality in La Unión 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 La Unión is worst in March — around 35 µg/m³ PM2.5 (moderate), about 1.8× the cleanest month (July, 19 µg/m³).

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

010203040JanFebMarAprMayJunJulAugSepOctNovDecModerateMar 1534 µg/m³Jul 1519 µg/m³
PM2.5 (µg/m³)Level
Jan28Moderate
Feb32Moderate
Mar35Moderate
Apr30Moderate
May24Moderate
Jun21Moderate
Jul19Moderate
Aug22Moderate
Sep25Moderate
Oct23Moderate
Nov22Moderate
Dec26Moderate
Location & terrain

Where is La Unión?

La Unión sits at 4.5°N, 76.1°W, 967 m above sea level, in Colombia. The nearest listed city is Roldanillo, 15 km away.

Topography around La Unión

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

Within 3 km, the terrain around La Unión has significant variations in elevation — a maximum elevation change of 504 m around an average of 1,031 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,272 m; within 80 km, extreme variations in elevation — a maximum elevation change of 4,598 m.

The land around La Unión is covered by grassland (62%) and trees (28%) within 3 km, grassland (50%) and trees (31%) within 16 km, and trees (74%) and grassland (23%) within 80 km.

3 km
504 m
16 km
1,272 m
80 km
4,598 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Roldanillo 15 km · Zarzal 16 km · Cartago 32 km · Sevilla 35 km · La Tebaida 36 km · Caicedonia 38 km · Quimbaya 39 km · Montenegro 39 km

Colombia travel facts

Travel advisory
Level 3
Reconsider Travel
Power plugs
Type A / B
120 / 240 V · 60 Hz
Prices
≈ 38% of US
price level, 2025
GDP per capita
$8,562
2025
Happiness
6.0 / 10
World Happiness, 2025
Safe drinking water
74%
of population, 2024
Homicide rate
24.9
per 100k, 2023
Road deaths
15.4
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Low
EF EPI 480
Religion
Roman Catholic 64%Protestant 17%none 14%atheist 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 La Unión (4.5328°, -76.1032°, elevation 967 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).