La Unión weather in May

In May, La Unión sees average daytime highs of 29°C and overnight lows near 27°C, with 277 mm of rain across 21.4 wet days and about 12.6 hours of daylight. It is the 5th-warmest and 4th-wettest month of the year here.

Day-to-day highs hold fairly steady near 29°C through the month. The sky is clear or mostly clear about 26% of the time in May, and the air most often feels oppressive.

Daylight stretches from about 12 h 30 min at the start of May to 12 h 42 min by month's end. Set against the rest of the year, May is La Unión's 8th-clearest and 8th-windiest month. For the whole year in context, see La Unión's year-round climate.

Daytime high
29°
5th warmest
Overnight low
27°
9th coldest
Rainfall
277 mm
21.4 wet days
Daylight
12 h 36 min
5:29 AM – 6:06 PM
Cloud cover
64%
8th clearest
Wind
10 km/h
8th windiest
Solar energy
6.05 kWh/m²
Travel score
4.0
out of 10

La Unión is city in El Salvador.

Density
186/km²
people per km²
Founded
1854

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 29°C through the month.

A typical May day in La Unión reaches about 29°C in the afternoon and slips back to 27°C overnight — a 3°C spread between the day's warmth and the night's chill. On most days the high lands between 28°C and 31°C. Set against its neighbours, May runs on par with April and on par with June.

25°28°30°33°35°151015202531
Avg high (°C)Avg low (°C)
13027
23027
33027
43027
53027
63027
73027
83027
93027
103027
113027
123027
133027
143027
152927
162927
172927
182927
192927
202926
212926
222926
232926
242926
252926
262926
272926
282926
292926
302926
312926

How May really feels in La Unión

Once humidity and wind are folded in, May averages 31 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
31
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

The story in May is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

La Unión weather by month

How May compares with the rest of the year at a glance. May is the 5th-warmest and 4th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan29° / 26°10.411.37.4
Feb29° / 26°20.611.67.4
Mar29° / 27°82.611.97.0
Apr29° / 27°409.912.35.6
May29° / 27°27721.412.64.0
Jun30° / 27°31320.912.83.8
Jul30° / 27°14612.412.74.5
Aug30° / 27°25619.212.44.1
Sep29° / 26°37525.112.13.6
Oct28° / 26°34422.111.74.2
Nov29° / 26°486.711.46.2
Dec29° / 26°30.911.27.2

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 26% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 15% of May, with mostly cloudy or overcast conditions the remaining 59%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16436
26238
36139
46139
55941
65842
75743
85644
95347
105149
114951
124753
134456
144258
154060
163862
173664
183466
193268
203268
212971
222971
232971
242674
252674
262674
272674
282575
292476
302476
312476

Chance of precipitation in May

Any precipitation

La Unión gets around 277 mm of rain over 21.4 wet days in May. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 69% and peaks near 83% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%80%151015202531
Rain chance (%)
151
252
353
454
554
655
756
857
958
1059
1161
1262
1364
1466
1568
1669
1771
1873
1975
2076
2178
2279
2380
2481
2582
2682
2783
2883
2983
3083
3183

Humidity in May

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, May lands in the oppressive band about 62% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202531
Muggy (%)Oppressive (%)Miserable (%)
125246
225246
325246
415445
515445
615445
715544
815544
915643
1005842
1105842
1205941
1306040
1406139
1506139
1606238
1706337
1806436
1906535
2006634
2106733
2206733
2306832
2406931
2506931
2606931
2706931
2806931
2906832
3006832
3106733

Wind in May

Winds average 10 km/h in May.

Across May, daily wind ranges from about 9 km/h on the calmest days to 11 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202531
Wind speed (km/h)Feels
111calm
211calm
311calm
411calm
511calm
611calm
711calm
811calm
911calm
1011calm
1111calm
1211calm
1311calm
1411calm
1510calm
1610calm
1710calm
1810calm
1910calm
2010calm
2110calm
2210calm
2310calm
2410calm
2510calm
2610calm
2710calm
2810calm
299calm
309calm
319calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 12 h 30 min at the start of May to 12 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 12 minutes over May. Sunrise moves from 5:35 AM to 5:27 AM, and sunset from 6:03 PM to 6:10 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
112.55:356:03
212.55:346:03
312.55:346:03
412.55:336:03
512.55:336:03
612.55:326:04
712.55:326:04
812.55:326:04
912.65:316:04
1012.65:316:05
1112.65:316:05
1212.65:306:05
1312.65:306:05
1412.65:306:06
1512.65:296:06
1612.65:296:06
1712.65:296:06
1812.65:296:07
1912.65:296:07
2012.65:286:07
2112.75:286:07
2212.75:286:08
2312.75:286:08
2412.75:286:08
2512.75:286:09
2612.75:276:09
2712.75:276:09
2812.75:276:10
2912.75:276:10
3012.75:276:10
3112.75:276:10

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 6.05 kWh/m².

For context, solar energy here swings from a low near 5.18 kWh/m² to a high of 6.78 kWh/m² in March across the year — May's 6.05 kWh/m² falls in the middle.

0246151015202531
Solar energy (kWh/m²)Level
16.5Intense
26.5Intense
36.5Intense
46.5Intense
56.5Intense
66.5Intense
76.5Intense
86.4Intense
96.4Intense
106.4Intense
116.3Intense
126.3Intense
136.2Intense
146.2Intense
156.1Intense
166.1Intense
176.0Intense
186.0Bright
195.9Bright
205.9Bright
215.8Bright
225.8Bright
235.8Bright
245.7Bright
255.7Bright
265.7Bright
275.6Bright
285.6Bright
295.6Bright
305.6Bright
315.6Bright
Planning a trip in May

Hazard calendar for La Unión

In seasonPeak

In May, La Unión sits inside its monsoon season. The full year is below, with each hazard's peak months called out.

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

La Unión's monsoon runs August–October, when most of the year's rain falls.

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

Is May a good time to visit La Unión?

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

4.0
Sightseeing
10th-best month of the year
5.2
Beach & pool
9th-best month of the year

May is a reasonable time to visit La Unión for sightseeing.

What to pack for La Unión in May

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

In May, La Unión sees daytime highs around 29°C and nights near 27°C. Pack light clothes, rain gear and sun protection. About 21 days see rain.

light clothesrain gearsun protection

Sea temperature near La Unión in May

The nearest coast averages about 30°C in May — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 24 km away) is warmest in August at about 30°C and coldest in January near 28°C.

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

26°28°30°32°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan28Warm
Feb28Warm
Mar28Tropical
Apr29Tropical
May30Tropical
Jun30Tropical
Jul30Tropical
Aug30Tropical
Sep30Tropical
Oct29Tropical
Nov29Tropical
Dec28Tropical

UV index in La Unión in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May peaks around 12 (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 March 20 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 14 at about 9 (very high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highMar 20UV 13Dec 14UV 9
UV index (midday)Level
Jan10Extreme
Feb12Extreme
Mar13Extreme
Apr13Extreme
May12Extreme
Jun13Extreme
Jul11Extreme
Aug11Extreme
Sep12Extreme
Oct11Extreme
Nov9Very high
Dec9Very high

Air quality in La Unión in May

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where May falls, not just the annual average.

Air quality in La Unión is worst in April — around 34 µg/m³ PM2.5 (moderate), about 3.3× the cleanest month (January, 10 µg/m³).

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

010203040JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 2233 µg/m³Jan 1010 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb12Good
Mar20Moderate
Apr34Moderate
May32Moderate
Jun21Moderate
Jul24Moderate
Aug20Moderate
Sep18Moderate
Oct17Moderate
Nov14Moderate
Dec10Good
Location & terrain

Where is La Unión?

La Unión sits at 13.3°N, 87.8°W, 10 m above sea level, in El Salvador. The nearest listed city is Langue, 37 km away.

LangueSan MiguelSan Francisco GoteraSan Rafael OrienteUsulutánSantiago de María

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 only modest variations in elevation — a maximum elevation change of 245 m around an average of 38 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,230 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,074 m.

The land around La Unión is covered by water (43%) and trees (33%) within 3 km, trees (39%) and water (32%) within 16 km, and trees (42%) and water (32%) within 80 km.

3 km
245 m
16 km
1,230 m
80 km
2,074 m
treesshrubsgrasslandcroplandartificial surfacesbare terrainwatermangroves
May weather nearby: Langue 37 km · San Miguel 40 km · San Lorenzo 44 km · San Francisco Gotera 49 km · San Rafael Oriente 55 km · Marcovia 58 km · Usulután 65 km · Santiago de María 69 km

El Salvador travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type A / B
115 V · 60 Hz
Prices
≈ 41% of US
price level, 2025
GDP per capita
$5,767
2025
Happiness
6.6 / 10
World Happiness, 2025
Homicide rate
7.9
per 100k, 2022
Road deaths
20.9
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Moderate
EF EPI 523
Religion
Roman Catholic 44%Protestant 40%none 16%

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 (13.3392°, -87.8433°, elevation 10 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).