Lạng Sơn weather in May

In May, Lạng Sơn sees average daytime highs of 29°C and overnight lows near 23°C, with 221 mm of rain across 21.2 wet days and about 13 hours of daylight. It is the 5th-warmest and 4th-wettest month of the year here.

Highs climb over the month, from about 28°C in the first days to 30°C by the end. The sky is clear or mostly clear about 10% of the time in May, and the air most often feels oppressive.

Daylight stretches from about 12 h 48 min at the start of May to 13 h 12 min by month's end. Set against the rest of the year, May is Lạng Sơn's 5th-clearest and 6th-windiest month. For the whole year in context, see Lạng Sơn's year-round climate.

Daytime high
29°
5th warmest
Overnight low
23°
8th coldest
Rainfall
221 mm
21.2 wet days
Daylight
13 hours
5:18 AM – 6:20 PM
Cloud cover
77%
5th clearest
Wind
10 km/h
6th windiest
Solar energy
4.61 kWh/m²
Travel score
4.0
out of 10

Lạng Sơn is provincial city of Vietnam.

Density
2,533/km²
people per km²
Founded
2002

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

Temperature in May

Average highAverage lowShaded bands: 10–90% of days

Highs climb over the month, from about 28°C in the first days to 30°C by the end.

A typical May day in Lạng Sơn reaches about 29°C in the afternoon and slips back to 23°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between 25°C and 33°C. Set against its neighbours, May runs about 3°C warmer than April and about 1°C cooler than June.

15°20°25°30°35°151015202531
Avg high (°C)Avg low (°C)
12822
22822
32822
42822
52822
62822
72922
82922
92922
102923
112923
122923
132923
142923
152923
162923
172923
182923
192923
202923
212923
222923
232923
243023
253023
263023
273024
283024
293024
303024
313024

How May really feels in Lạng Sơn

Once humidity and wind are folded in, May averages 17 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
17
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.

Lạng Sơn 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
Jan17° / 11°5711.110.85.1
Feb19° / 13°4410.111.25.6
Mar21° / 16°7914.411.85.5
Apr26° / 20°9714.912.55.5
May29° / 23°22121.2134.0
Jun30° / 25°25723.613.33.0
Jul31° / 25°27024.913.22.9
Aug30° / 24°28525.312.73.0
Sep29° / 23°16418.312.14.2
Oct27° / 20°7510.911.56.4
Nov23° / 16°507.9117.1
Dec19° / 12°458.210.76.3

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 10% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 12% of May, with mostly cloudy or overcast conditions the remaining 78%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
12476
22476
32575
42674
52674
62674
72674
82674
92674
102575
112575
122476
132476
142476
152476
162278
172278
182278
192179
202179
212080
222080
231981
241882
251882
261882
271783
281783
291684
301585
311585

Chance of precipitation in May

Any precipitation

Lạng Sơn gets around 221 mm of rain over 21.2 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 68% and peaks near 74% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%80%151015202531
Rain chance (%)
160
261
362
463
564
665
766
866
967
1067
1168
1268
1368
1468
1568
1668
1769
1869
1969
2069
2169
2270
2370
2470
2571
2671
2772
2872
2973
3073
3174

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 47% of days. Sticky, muggy-or-worse air turns up on roughly 90% of them.

0%25%50%75%100%151015202531
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1051024547
2051023548
3041023549
4049225510
5049215511
6039205513
7039205414
8039195316
9039185317
10039175219
11139175020
12129175022
13129164923
14128164825
15128164726
16128164627
17128164529
18128154430
19128154431
20117154333
21017154234
22016154235
23016154136
24016154137
25015144139
26015144140
27014134142
28014124043
29013114045
30013113947
31012103948

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
710calm
810calm
910calm
1010calm
1110calm
1210calm
1310calm
1410calm
1510calm
1610calm
1710calm
1810calm
1910calm
2010calm
2110calm
229calm
239calm
249calm
259calm
269calm
279calm
289calm
299calm
309calm
319calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 12 h 48 min at the start of May to 13 h 12 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 24 minutes over May. Sunrise moves from 5:26 AM to 5:14 AM, and sunset from 6:14 PM to 6:27 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:266:14
212.85:266:14
312.85:256:15
412.85:246:15
512.95:246:16
612.95:236:16
712.95:236:16
812.95:226:17
912.95:216:17
1012.95:216:18
1113.05:206:18
1213.05:206:19
1313.05:196:19
1413.05:196:20
1513.05:186:20
1613.05:186:20
1713.15:186:21
1813.15:176:21
1913.15:176:22
2013.15:166:22
2113.15:166:23
2213.15:166:23
2313.15:156:24
2413.15:156:24
2513.25:156:24
2613.25:156:25
2713.25:146:25
2813.25:146:26
2913.25:146:26
3013.25:146:27
3113.25:146:27

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 4.61 kWh/m².

For context, solar energy here swings from a low near 2.23 kWh/m² to a high of 4.72 kWh/m² in July across the year — May's 4.61 kWh/m² sits near the top of that range.

024151015202531
Solar energy (kWh/m²)Level
14.5Bright
24.6Bright
34.6Bright
44.6Bright
54.6Bright
64.6Bright
74.6Bright
84.6Bright
94.6Bright
104.6Bright
114.6Bright
124.6Bright
134.6Bright
144.6Bright
154.6Bright
164.6Bright
174.6Bright
184.6Bright
194.6Bright
204.6Bright
214.6Bright
224.6Bright
234.6Bright
244.6Bright
254.6Bright
264.6Bright
274.6Bright
284.6Bright
294.6Bright
304.6Bright
314.6Bright
Planning a trip in May

Hazard calendar for Lạng Sơn

In seasonPeak

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

Lạng Sơn's monsoon runs May–September, when most of the year's rain falls.

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

Is May a good time to visit Lạng Sơn?

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

4.0
Sightseeing
9th-best month of the year
5.0
Beach & pool
5th-best month of the year

May is a reasonable time to visit Lạng Sơn for sightseeing.

What to pack for Lạng Sơn in May

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

In May, Lạng Sơn sees daytime highs around 29°C and nights near 23°C. Pack light clothes and rain gear. Worth having: sun protection. About 21 days see rain.

light clothesrain gearsun protection

UV index in Lạng Sơn in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May 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 Lạng Sơn peaks around June 23 at about 12 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 14 at about 6 (high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecHighVery highVery highExtremeVery highHighJun 23UV 12Dec 14UV 6
UV index (midday)Level
Jan6High
Feb7High
Mar9Very high
Apr7High
May9Very high
Jun12Extreme
Jul12Extreme
Aug10Extreme
Sep10Very high
Oct8Very high
Nov6High
Dec6High

Air quality in Lạng Sơn 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 Lạng Sơn is worst in December — around 58 µg/m³ PM2.5 (unhealthy), about 2.3× the cleanest month (July, 25 µg/m³).

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

0204060JanFebMarAprMayJunJulAugSepOctNovDecUnhealthyPoorModeratePoorUnhealthyDec 2358 µg/m³Jul 1625 µg/m³
PM2.5 (µg/m³)Level
Jan57Unhealthy
Feb55Unhealthy
Mar55Poor
Apr54Poor
May37Poor
Jun29Moderate
Jul25Moderate
Aug29Moderate
Sep36Poor
Oct43Poor
Nov50Poor
Dec58Unhealthy
Location & terrain

Where is Lạng Sơn?

Lạng Sơn sits at 21.9°N, 106.8°E, 265 m above sea level, in Vietnam. The nearest listed city is Thị Trấn Na Dương, 26 km away.

Topography around Lạng Sơn

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

Within 3 km, the terrain around Lạng Sơn has only modest variations in elevation — a maximum elevation change of 171 m around an average of 282 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 978 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,481 m.

The land around Lạng Sơn is covered by trees (46%) and artificial surfaces (32%) within 3 km, trees (80%) within 16 km, and trees (89%) within 80 km.

3 km
171 m
16 km
978 m
80 km
1,481 m
treesgrasslandcroplandartificial surfacesbare terrainwater
May weather nearby: Thị Trấn Na Dương 26 km · Thị Trấn Thất Khê 54 km · Chũ 57 km · Thị Trấn Ba Chẽ 84 km · Bắc Giang 87 km · Thị Trấn Tiên Yên 88 km · Thị Trấn Đông Triều 89 km · Thị Trấn Mạo Khê 90 km

Vietnam travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type A / B / C / F
220 V · 50 Hz
Prices
≈ 29% of US
price level, 2025
GDP per capita
$5,066
2025
Happiness
6.4 / 10
World Happiness, 2025
Safe drinking water
59%
of population, 2024
Homicide rate
1.5
per 100k, 2011
Road deaths
30.6
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Moderate
EF EPI 500
Religion
none 86%Catholic 6%Buddhist 6%Protestant 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 Lạng Sơn (21.8526°, 106.761°, elevation 265 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).