Mae Sai weather in May

In May, Mae Sai sees average daytime highs of 33°C and overnight lows near 23°C, with 277 mm of rain across 21.3 wet days and about 13 hours of daylight. It is the 3rd-warmest and 5th-wettest month of the year here.

Day-to-day highs hold fairly steady near 33°C through the month. The sky is clear or mostly clear about 24% of the time in May, and the air most often feels oppressive.

Daylight stretches from about 12 h 42 min at the start of May to 13 h 06 min by month's end. Set against the rest of the year, May is Mae Sai's 8th-clearest and 5th-windiest month. For the whole year in context, see Mae Sai's year-round climate.

Daytime high
33°
3rd warmest
Overnight low
23°
8th coldest
Rainfall
277 mm
21.3 wet days
Daylight
13 hours
5:48 AM – 6:46 PM
Cloud cover
67%
8th clearest
Wind
4 km/h
5th windiest
Solar energy
5.38 kWh/m²
Travel score
2.8
out of 10

Mae Sai is subdistrict municipality in Chiang Rai province, Thailand.

Density
5,365/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 33°C through the month.

A typical May day in Mae Sai reaches about 33°C in the afternoon and slips back to 23°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 28°C and 36°C. Set against its neighbours, May runs about 1°C cooler than April and about 1°C warmer than June.

20°25°30°35°40°151015202531
Avg high (°C)Avg low (°C)
13322
23322
33322
43323
53323
63323
73323
83323
93323
103323
113323
123323
133323
143323
153323
163223
173223
183223
193223
203223
213223
223224
233224
243224
253224
263224
273224
283224
293224
303224
313224

How May really feels in Mae Sai

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.

Mae Sai weather by month

How May compares with the rest of the year at a glance. May is the 3rd-warmest and 5th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan27° / 14°253.410.97.9
Feb30° / 14°152.411.36.1
Mar33° / 17°395.111.94.2
Apr34° / 21°11210.712.53.2
May33° / 23°27721.3132.8
Jun32° / 24°34926.713.22.4
Jul31° / 24°45528.513.12.5
Aug31° / 24°42428.712.72.6
Sep31° / 23°28724.212.13.0
Oct30° / 22°13416.711.54.3
Nov29° / 18°476.5116.5
Dec26° / 15°314.410.87.9

Cloud cover in May

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 24% of the time in May.

Beyond those clear spells, partly cloudy skies cover about 16% of May, with mostly cloudy or overcast conditions the remaining 60%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
16733
26634
36634
46436
56238
66139
75941
85644
95545
105248
115050
124852
134654
144456
154258
163961
173862
183565
193367
203268
212971
222773
232674
242575
252377
262278
272080
281981
291783
301684
311585

Chance of precipitation in May

Any precipitation

Mae Sai gets around 277 mm of rain over 21.3 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 68% and peaks near 84% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%80%151015202531
Rain chance (%)
153
254
355
456
557
658
759
860
962
1063
1164
1265
1366
1467
1568
1669
1769
1870
1971
2072
2173
2274
2375
2476
2577
2678
2779
2881
2982
3083
3184

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 78% of days. Sticky, muggy-or-worse air turns up on roughly 99% of them.

0%25%50%75%100%151015202531
Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1229681
2227701
3225721
4223741
5222742
6220762
7218782
8216802
9215803
10214813
11213814
12212824
13111835
14110845
1519846
1618847
1718838
1817848
1916849
20168211
21158212
22158113
23157915
24147916
25147718
26137620
27037522
28037324
29027226
30027028
31026731

Wind in May

Winds average 4 km/h in May.

Across May, daily wind ranges from about 4 km/h on the calmest days to 4 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202531
Wind speed (km/h)Feels
14calm
24calm
34calm
44calm
54calm
64calm
74calm
84calm
94calm
104calm
114calm
124calm
134calm
144calm
154calm
164calm
174calm
184calm
194calm
204calm
214calm
224calm
234calm
244calm
254calm
264calm
274calm
284calm
294calm
304calm
314calm

Sunrise & sunset in May

DaylightNight

Daylight runs from about 12 h 42 min at the start of May to 13 h 06 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 5:56 AM to 5:44 AM, and sunset from 6:40 PM to 6:52 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
112.75:566:40
212.85:556:40
312.85:546:41
412.85:546:41
512.85:536:41
612.85:536:42
712.85:526:42
812.95:516:42
912.95:516:43
1012.95:506:43
1112.95:506:44
1212.95:496:44
1312.95:496:45
1412.95:496:45
1513.05:486:45
1613.05:486:46
1713.05:476:46
1813.05:476:47
1913.05:476:47
2013.05:466:47
2113.05:466:48
2213.05:466:48
2313.15:456:49
2413.15:456:49
2513.15:456:50
2613.15:456:50
2713.15:446:50
2813.15:446:51
2913.15:446:51
3013.15:446:52
3113.15:446:52

Solar energy in May

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in May, about 5.38 kWh/m².

For context, solar energy here swings from a low near 3.91 kWh/m² to a high of 6.25 kWh/m² in April across the year — May's 5.38 kWh/m² sits near the top of that range.

0246151015202531
Solar energy (kWh/m²)Level
15.9Bright
25.9Bright
35.9Bright
45.8Bright
55.8Bright
65.8Bright
75.7Bright
85.7Bright
95.7Bright
105.6Bright
115.6Bright
125.5Bright
135.5Bright
145.4Bright
155.4Bright
165.4Bright
175.3Bright
185.3Bright
195.3Bright
205.2Bright
215.2Bright
225.2Bright
235.1Bright
245.1Bright
255.1Bright
265.0Bright
275.0Bright
285.0Bright
294.9Bright
304.9Bright
314.9Bright
Planning a trip in May

Hazard calendar for Mae Sai

In seasonPeak

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

Mae Sai'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 Mae Sai?

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

2.8
Sightseeing
9th-best month of the year
4.7
Beach & pool
8th-best month of the year

May is a weaker month for outdoor sightseeing in Mae Sai.

What to pack for Mae Sai in May

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

In May, Mae Sai sees daytime highs around 33°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 Mae Sai 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 Mae Sai peaks around July 19 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 20 at about 7 (high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecVery highExtremeVery highHighJul 19UV 13Dec 20UV 7
UV index (midday)Level
Jan7High
Feb9Very high
Mar9Very high
Apr10Very high
May11Extreme
Jun13Extreme
Jul13Extreme
Aug13Extreme
Sep11Extreme
Oct10Extreme
Nov8Very high
Dec7High

Air quality in Mae Sai 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 Mae Sai is worst in April — around 156 µg/m³ PM2.5 (very unhealthy), about 12.0× the cleanest month (July, 13 µg/m³).

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

0306090120150180JanFebMarAprMayJunJulAugSepOctNovDecModerateUnhealthyModerateApr 11150 µg/m³Jul 2313 µg/m³
PM2.5 (µg/m³)Level
Jan23Moderate
Feb40Poor
Mar128Unhealthy
Apr156Very unhealthy
May37Poor
Jun15Moderate
Jul13Moderate
Aug13Moderate
Sep13Moderate
Oct14Moderate
Nov15Moderate
Dec19Moderate
Location & terrain

Where is Mae Sai?

Mae Sai sits at 20.4°N, 99.9°E, 437 m above sea level, in Thailand. The nearest listed city is Tachilek, 2.0 km away.

Möng YawngPhayao

Topography around Mae Sai

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

Within 3 km, the terrain around Mae Sai has significant variations in elevation — a maximum elevation change of 398 m around an average of 464 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,235 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,977 m.

The land around Mae Sai is covered by trees (54%) and artificial surfaces (33%) within 3 km, trees (61%) and cropland (27%) within 16 km, and trees (81%) within 80 km.

3 km
398 m
16 km
1,235 m
80 km
1,977 m
treesgrasslandcroplandartificial surfaces
May weather nearby: Tachilek 2.0 km · Ban Khoan 24 km · Mae Chan 32 km · Chiang Rai 59 km · Ban Houakhoua 64 km · Möng Yawng 97 km · Kengtung 133 km · Phayao 138 km

Thailand travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type A / B / C
230 V · 50 Hz
Prices
≈ 31% of US
price level, 2025
GDP per capita
$8,057
2025
Happiness
6.3 / 10
World Happiness, 2025
Homicide rate
4.8
per 100k, 2011
Road deaths
32.2
per 100k/yr, 2019
Income group
Upper middle
World Bank
English
Very low
EF EPI 402
Religion
Buddhist 93%Muslim 5%Christian 1%other 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 Mae Sai (20.4335°, 99.8762°, elevation 437 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).