Sơn La weather in May

In May, Sơn La sees average daytime highs of 30°C and overnight lows near 22°C, with 147 mm of rain across 19.3 wet days and about 13 hours of daylight. It is the 1st-warmest and 5th-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 17% 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 Sơn La's 8th-clearest and 8th-windiest month. For the whole year in context, see Sơn La's year-round climate.

Daytime high
30°
1st warmest
Overnight low
22°
9th coldest
Rainfall
147 mm
19.3 wet days
Daylight
13 hours
5:30 AM – 6:31 PM
Cloud cover
73%
8th clearest
Wind
5 km/h
8th windiest
Solar energy
5.1 kWh/m²
Travel score
3.7
out of 10

Sơn La is the old provincial capital of Son La province, Vietnam.

Density
328/km²
people per km²

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 30°C through the month.

A typical May day in Sơn La reaches about 30°C in the afternoon and slips back to 22°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 26°C and 34°C. Set against its neighbours, May runs about 1°C warmer than April and on par with June.

15°20°25°30°35°151015202531
Avg high (°C)Avg low (°C)
13021
23021
33021
43021
53021
63021
73021
83021
93021
103021
113021
123022
133022
143022
153022
163022
173022
183022
193022
203022
213022
223022
233022
243022
253022
263022
273022
283022
293022
303023
313023

How May really feels in Sơn La

Once humidity and wind are folded in, May averages 26 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
26
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.

Sơn La weather by month

How May compares with the rest of the year at a glance. May is the 1st-warmest and 5th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan21° / 12°24410.87.3
Feb23° / 13°193.611.37.9
Mar27° / 16°507.111.87.1
Apr29° / 19°7212.812.55.2
May30° / 22°14719.3133.7
Jun30° / 23°2092313.33.2
Jul29° / 23°28824.513.23.4
Aug29° / 22°28325.312.73.4
Sep29° / 21°15017.512.14.4
Oct27° / 19°498.311.56.6
Nov25° / 16°274.5117.8
Dec22° / 12°233.610.77.6

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 17% 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 69%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
15149
24951
34951
44852
54852
64753
74654
84456
94357
104258
113961
123862
133763
143565
153367
163268
173070
182872
192773
202575
212377
222179
232179
241981
251882
261783
271585
281486
291486
301288
311288

Chance of precipitation in May

Any precipitation

Sơn La gets around 147 mm of rain over 19.3 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 62% and peaks near 75% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%80%151015202531
Rain chance (%)
152
253
354
454
555
655
756
856
957
1058
1158
1259
1360
1460
1561
1661
1762
1863
1964
2064
2165
2266
2367
2468
2569
2670
2771
2872
2973
3074
3175

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 49% of days. Sticky, muggy-or-worse air turns up on roughly 89% of them.

0%25%50%75%100%151015202531
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
14166119
24156120
34155922
44145923
54145725
64135528
73125530
83115432
93115234
103105136
11394939
12394741
13384643
14374446
15374248
16364051
17363952
18363754
19253657
20253459
21253261
22253162
23252964
24142867
25142669
26142471
27142372
28132175
29132076
30131878
31021781

Wind in May

Winds average 5 km/h in May.

Across May, daily wind ranges from about 5 km/h on the calmest days to 5 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (km/h)Feels
15calm
25calm
35calm
45calm
55calm
65calm
75calm
85calm
95calm
105calm
115calm
125calm
135calm
145calm
155calm
165calm
175calm
185calm
195calm
205calm
215calm
225calm
235calm
245calm
255calm
265calm
275calm
285calm
295calm
305calm
315calm

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 5:38 AM to 5:26 AM, and sunset from 6:25 PM to 6:37 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
112.85:386:25
212.85:386:25
312.85:376:26
412.85:366:26
512.85:366:26
612.95:356:27
712.95:356:27
812.95:346:28
912.95:346:28
1012.95:336:28
1112.95:326:29
1213.05:326:29
1313.05:316:30
1413.05:316:30
1513.05:316:31
1613.05:306:31
1713.05:306:31
1813.05:296:32
1913.15:296:32
2013.15:296:33
2113.15:286:33
2213.15:286:34
2313.15:286:34
2413.15:276:34
2513.15:276:35
2613.15:276:35
2713.25:276:36
2813.25:266:36
2913.25:266:37
3013.25:266:37
3113.25:266:37

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.1 kWh/m².

For context, solar energy here swings from a low near 3.14 kWh/m² to a high of 5.26 kWh/m² in April across the year — May's 5.1 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.4Bright
25.4Bright
35.4Bright
45.3Bright
55.3Bright
65.3Bright
75.3Bright
85.3Bright
95.3Bright
105.3Bright
115.2Bright
125.2Bright
135.2Bright
145.2Bright
155.1Bright
165.1Bright
175.1Bright
185.0Bright
195.0Bright
205.0Bright
215.0Bright
225.0Bright
234.9Bright
244.9Bright
254.9Bright
264.9Bright
274.8Bright
284.8Bright
294.8Bright
304.8Bright
314.8Bright
Planning a trip in May

Hazard calendar for Sơn La

In seasonPeak

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

Sơn La'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 Sơn La?

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

3.7
Sightseeing
9th-best month of the year
5.2
Beach & pool
7th-best month of the year

May is a weaker month for outdoor sightseeing in Sơn La.

What to pack for Sơn La in May

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

In May, Sơn La sees daytime highs around 30°C and nights near 22°C. Pack light clothes and rain gear. Worth having: sun protection. About 19 days see rain.

light clothesrain gearsun protection

UV index in Sơn La in May

LowModerateHighVery highExtreme

Clear-sky midday UV in May 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 Sơn La peaks around June 20 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 18 at about 6 (high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecVery highExtremeVery highExtremeVery highHighJun 20UV 13Dec 18UV 6
UV index (midday)Level
Jan7Very high
Feb9Very high
Mar11Extreme
Apr9Very high
May11Extreme
Jun14Extreme
Jul13Extreme
Aug13Extreme
Sep9Very high
Oct9Very high
Nov8Very high
Dec6High

Air quality in Sơn La 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 Sơn La is worst in April — around 151 µg/m³ PM2.5 (very unhealthy), about 12.9× the cleanest month (August, 12 µg/m³).

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

0306090120150JanFebMarAprMayJunJulAugSepOctNovDecModeratePoorUnhealthyModerateGoodModerateApr 16140 µg/m³Aug 912 µg/m³
PM2.5 (µg/m³)Level
Jan32Moderate
Feb38Poor
Mar67Unhealthy
Apr151Very unhealthy
May58Unhealthy
Jun14Moderate
Jul12Good
Aug12Good
Sep16Moderate
Oct23Moderate
Nov26Moderate
Dec31Moderate
Location & terrain

Where is Sơn La?

Sơn La sits at 21.3°N, 103.9°E, 608 m above sea level, in Vietnam. The nearest listed city is Ít Ong, 24 km away.

Dien Bien PhuXam NuaVieng XaiMường LayYên Bái

Topography around Sơn La

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

Within 3 km, the terrain around Sơn La has significant variations in elevation — a maximum elevation change of 348 m around an average of 674 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,404 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,830 m.

The land around Sơn La is covered by trees (59%) within 3 km, trees (69%) and grassland (21%) within 16 km, and trees (68%) and grassland (27%) within 80 km.

3 km
348 m
16 km
1,404 m
80 km
2,830 m
treesgrasslandcroplandartificial surfacesbare terrainwater
May weather nearby: Ít Ong 24 km · Thị Trấn Thuận Châu 27 km · Nghĩa Lộ 69 km · Dien Bien Phu 93 km · Xam Nua 102 km · Vieng Xai 107 km · Mường Lay 111 km · Yên Bái 112 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 Sơn La (21.3256°, 103.9188°, elevation 608 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).