La Unión weather in December

In December, La Unión sees average daytime highs of 29°C and overnight lows near 26°C, with 3 mm of rain across 0.9 wet days and about 11.2 hours of daylight. It is the 7th-warmest and 10th-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 79% of the time in December, and the air most often feels oppressive.

Daylight stretches from about 11 h 18 min at the start of December to 11 h 12 min by month's end. Set against the rest of the year, December is La Unión's 4th-clearest and 4th-windiest month. For the whole year in context, see La Unión's year-round climate.

Daytime high
29°
7th warmest
Overnight low
26°
4th coldest
Rainfall
3 mm
0.9 wet days
Daylight
11 h 12 min
6:11 AM – 5:24 PM
Cloud cover
24%
4th clearest
Wind
13 km/h
4th windiest
Solar energy
5.48 kWh/m²
Travel score
7.2
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 December

Average highAverage lowShaded bands: 10–90% of days

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

A typical December day in La Unión reaches about 29°C in the afternoon and slips back to 26°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 30°C. Set against its neighbours, December runs on par with November and on par with January.

20°25°30°35°151015202531
Avg high (°C)Avg low (°C)
12926
22926
32926
42926
52926
62926
72926
82926
92926
102926
112926
122926
132926
142926
152926
162926
172926
182926
192926
202926
212926
222926
232926
242926
252926
262926
272926
282926
292926
302926
312926

How December really feels in La Unión

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

December sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

La Unión weather by month

How December compares with the rest of the year at a glance. December is the 7th-warmest and 10th-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 December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 79% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 8% of December, with mostly cloudy or overcast conditions the remaining 13%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
18020
28119
38218
48416
58416
68515
78515
88614
98614
108614
118713
128713
138713
148713
158713
168713
178713
188812
198911
208911
219010
229010
239010
249010
25919
26919
27919
28919
29919
30919
319010

Chance of precipitation in December

Any precipitation

La Unión gets around 3 mm of rain over 0.9 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 3% and peaks near 6% on the wettest days.

0%10%20%30%151015202531
Rain chance (%)
16
25
35
44
54
64
73
83
93
103
113
123
133
143
153
163
173
183
193
203
213
223
233
243
252
262
272
282
292
302
312

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the oppressive band about 54% of days. Sticky, muggy-or-worse air turns up on roughly 93% of them.

0%25%50%75%100%151015202531
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
10731602
20732592
30732592
40633592
51633582
61634572
71634572
81634572
91634581
101633591
111634581
121634581
132634571
142634571
152635561
162636551
172637541
182638531
191639531
201639531
211640521
221641511
231642501
241642501
251643491
261643491
271644481
281644481
290644481
301745471
311745471

Wind in December

Winds average 13 km/h in December.

Across December, daily wind ranges from about 12 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
112light breeze
212light breeze
312light breeze
412light breeze
512light breeze
612light breeze
712light breeze
813light breeze
913light breeze
1013light breeze
1113light breeze
1213light breeze
1313light breeze
1413light breeze
1513light breeze
1613light breeze
1713light breeze
1813light breeze
1913light breeze
2013light breeze
2113light breeze
2214light breeze
2314light breeze
2414light breeze
2514light breeze
2614light breeze
2714light breeze
2814light breeze
2914light breeze
3014light breeze
3114light breeze

Sunrise & sunset in December

DaylightNight

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

Days shrink by about 6 minutes over December. Sunrise moves from 6:03 AM to 6:18 AM, and sunset from 5:19 PM to 5:31 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
111.36:035:19
211.36:045:19
311.36:045:20
411.36:055:20
511.36:055:20
611.26:065:21
711.26:065:21
811.26:075:21
911.26:075:21
1011.26:085:22
1111.26:085:22
1211.26:095:22
1311.26:095:23
1411.26:105:23
1511.26:105:24
1611.26:115:24
1711.26:125:24
1811.26:125:25
1911.26:135:25
2011.26:135:26
2111.26:135:26
2211.26:145:27
2311.26:145:27
2411.26:155:28
2511.26:155:28
2611.26:165:29
2711.26:165:29
2811.26:175:30
2911.26:175:30
3011.26:175:31
3111.26:185:31

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 5.48 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 — December's 5.48 kWh/m² sits near the bottom.

0246151015202531
Solar energy (kWh/m²)Level
15.4Bright
25.4Bright
35.5Bright
45.5Bright
55.5Bright
65.5Bright
75.5Bright
85.4Bright
95.4Bright
105.4Bright
115.4Bright
125.4Bright
135.4Bright
145.4Bright
155.4Bright
165.4Bright
175.4Bright
185.4Bright
195.5Bright
205.5Bright
215.5Bright
225.5Bright
235.5Bright
245.5Bright
255.5Bright
265.5Bright
275.5Bright
285.5Bright
295.5Bright
305.5Bright
315.6Bright
Planning a trip in December

Hazard calendar for La Unión

In seasonPeak

None of La Unión's seasonal hazards are active in December. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

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 December a good time to visit La Unión?

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

7.2
Sightseeing
3rd-best month of the year
9.2
Beach & pool
3rd-best month of the year

December is one of the better times to visit La Unión for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for La Unión in December

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

In December, La Unión sees daytime highs around 29°C and nights near 26°C. Pack light clothes. Worth having: sun protection.

light clothessun protection

Sea temperature near La Unión in December

The nearest coast averages about 28°C in December — 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 December

LowModerateHighVery highExtreme

Clear-sky midday UV in December 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 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 December

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where December 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
December 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).