Ko Samui weather in April

In April, Ko Samui sees average daytime highs of 29°C and overnight lows near 28°C, with 95 mm of rain across 11.7 wet days and about 12.2 hours of daylight. It is the 3rd-warmest and 6th-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 36% of the time in April, and the air most often feels miserable.

Daylight stretches from about 12 h 06 min at the start of April to 12 h 18 min by month's end. Set against the rest of the year, April is Ko Samui's 4th-clearest and 12th-windiest month. For the whole year in context, see Ko Samui's year-round climate.

Daytime high
29°
3rd warmest
Overnight low
28°
12th coldest
Rainfall
95 mm
11.7 wet days
Daylight
12 h 12 min
6:14 AM – 6:27 PM
Cloud cover
55%
4th clearest
Wind
14 km/h
12th windiest
Solar energy
6.44 kWh/m²
Travel score
5.3
out of 10

Ko Samui is city in Surat Thani province, Thailand.

Density
219/km²
people per km²
Founded
1956

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

Temperature in April

Average highAverage lowShaded bands: 10–90% of days

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

A typical April day in Ko Samui reaches about 29°C in the afternoon and slips back to 28°C overnight — a 2°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, April runs about 1°C warmer than March and on par with May.

25°28°30°33°35°151015202530
Avg high (°C)Avg low (°C)
12927
22927
32927
42927
52927
62927
72927
82927
92927
102927
112927
122928
132928
142928
152928
162928
172928
182928
192928
202928
212928
222928
232928
242928
252928
262928
272928
282928
292928
302928

How April really feels in Ko Samui

Once humidity and wind are folded in, April averages 30 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
30
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

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

Ko Samui weather by month

How April compares with the rest of the year at a glance. April is the 3rd-warmest and 6th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan27° / 26°769.411.56.7
Feb27° / 26°355.311.77.3
Mar28° / 27°888.411.96.4
Apr29° / 28°9511.712.25.3
May29° / 27°11621.212.43.8
Jun29° / 27°8918.812.53.9
Jul29° / 27°8418.412.54.2
Aug29° / 27°911812.34.3
Sep28° / 27°14022.812.13.9
Oct28° / 26°2862611.83.9
Nov28° / 26°28920.911.64.6
Dec27° / 26°14513.211.55.9

Cloud cover in April

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 36% of the time in April.

Beyond those clear spells, partly cloudy skies cover about 16% of April, with mostly cloudy or overcast conditions the remaining 48%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15941
25941
35743
45743
55743
65545
75545
85545
95545
105446
115446
125446
135446
145446
155446
165446
175446
185347
195347
205248
215149
225149
235050
244951
254852
264753
274654
284555
294357
304258

Chance of precipitation in April

Any precipitation

Ko Samui gets around 95 mm of rain over 11.7 wet days in April. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 40% and peaks near 56% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
135
235
335
434
534
634
734
835
935
1035
1135
1235
1335
1435
1535
1636
1736
1837
1938
2040
2141
2242
2344
2445
2547
2648
2750
2852
2954
3056

Humidity in April

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, April lands in the miserable band about 79% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Oppressive (%)Miserable (%)
13862
23664
33565
43367
53268
63169
73070
82971
92872
102773
112575
122476
132377
142179
152080
161981
171882
181783
191684
201486
211486
221387
231288
241189
251189
261090
271090
281090
29991
30991

Wind in April

Winds average 14 km/h in April, the calmest month.

Across April, daily wind ranges from about 13 km/h on the calmest days to 15 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
115light breeze
215light breeze
315light breeze
415light breeze
514light breeze
614light breeze
714light breeze
814light breeze
914light breeze
1014light breeze
1114light breeze
1214light breeze
1314light breeze
1414light breeze
1514light breeze
1614light breeze
1714light breeze
1814light breeze
1914light breeze
2014light breeze
2114light breeze
2214light breeze
2314light breeze
2414light breeze
2513light breeze
2613light breeze
2713light breeze
2813light breeze
2913light breeze
3013light breeze

Sunrise & sunset in April

DaylightNight

Daylight runs from about 12 h 06 min at the start of April to 12 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 12 minutes over April. Sunrise moves from 6:23 AM to 6:08 AM, and sunset from 6:27 PM to 6:27 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.16:236:27
212.16:226:27
312.16:216:27
412.16:216:27
512.16:206:27
612.16:206:27
712.16:196:27
812.16:186:27
912.16:186:27
1012.26:176:27
1112.26:176:27
1212.26:166:27
1312.26:166:27
1412.26:156:27
1512.26:156:27
1612.26:146:27
1712.26:146:27
1812.26:136:27
1912.26:136:27
2012.26:126:27
2112.36:126:27
2212.36:116:27
2312.36:116:27
2412.36:106:27
2512.36:106:27
2612.36:096:27
2712.36:096:27
2812.36:096:27
2912.36:086:27
3012.36:086:27

Solar energy in April

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in April, about 6.44 kWh/m² — the sunniest month for solar.

For context, solar energy here swings from a low near 4.49 kWh/m² to a high of 6.44 kWh/m² in April across the year — April's 6.44 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
16.4Intense
26.4Intense
36.4Intense
46.4Intense
56.4Intense
66.4Intense
76.5Intense
86.5Intense
96.5Intense
106.5Intense
116.5Intense
126.5Intense
136.5Intense
146.5Intense
156.5Intense
166.5Intense
176.5Intense
186.5Intense
196.5Intense
206.5Intense
216.5Intense
226.4Intense
236.4Intense
246.4Intense
256.4Intense
266.3Intense
276.3Intense
286.3Intense
296.3Intense
306.2Intense
Planning a trip in April

Hazard calendar for Ko Samui

In seasonPeak

In April, Ko Samui sits inside its cyclone season. The full year is below, with each hazard's peak months called out.

Ko Samui sits in the North Indian Ocean cyclone zone; the season peaks May and October–November.

Ko Samui's rainy season runs September–December, when most of the year's rain falls.

Cyclone
Rainy season
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is April a good time to visit Ko Samui?

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

5.3
Sightseeing
5th-best month of the year
6.7
Beach & pool
4th-best month of the year

April is a reasonable time to visit Ko Samui for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Ko Samui in April

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

In April, Ko Samui sees daytime highs around 29°C and nights near 28°C. Pack light clothes and sun protection. Worth having: rain gear. About 12 days see rain.

light clothessun protectionrain gear

Sea temperature near Ko Samui in April

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

The sea offshore is warmest in May 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
Feb28Tropical
Mar29Tropical
Apr30Tropical
May30Tropical
Jun30Tropical
Jul30Tropical
Aug29Tropical
Sep29Tropical
Oct29Tropical
Nov29Tropical
Dec28Warm

UV index in Ko Samui in April

LowModerateHighVery highExtreme

Clear-sky midday UV in April peaks around 13 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Ko Samui peaks around August 22 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 18 at about 10 (very high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highAug 22UV 14Dec 18UV 10
UV index (midday)Level
Jan10Very high
Feb12Extreme
Mar13Extreme
Apr13Extreme
May13Extreme
Jun12Extreme
Jul11Extreme
Aug14Extreme
Sep13Extreme
Oct11Extreme
Nov10Extreme
Dec10Very high

Air quality in Ko Samui in April

GoodModeratePoorUnhealthyVery unhealthy

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

Air quality in Ko Samui is worst in January — around 16 µg/m³ PM2.5 (moderate), and holds fairly steady the rest of the year.

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

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodJan 2016 µg/m³Nov 1110 µg/m³
PM2.5 (µg/m³)Level
Jan16Moderate
Feb15Moderate
Mar13Moderate
Apr14Moderate
May13Moderate
Jun14Moderate
Jul15Moderate
Aug12Good
Sep12Good
Oct11Good
Nov10Good
Dec12Moderate
Location & terrain

Where is Ko Samui?

Ko Samui sits at 9.5°N, 99.9°E, 8 m above sea level, in Thailand. The nearest listed city is Ko Pha-ngan, 27 km away.

Ban Na SanLang SuanNakhon Si ThammaratPak Phanang

Topography around Ko Samui

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

Within 3 km, the terrain around Ko Samui has significant variations in elevation — a maximum elevation change of 476 m around an average of 56 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 629 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,358 m.

The land around Ko Samui is covered by trees (51%) and water (42%) within 3 km, water (72%) and trees (24%) within 16 km, and water (82%) within 80 km.

3 km
476 m
16 km
629 m
80 km
1,358 m
treesgrasslandartificial surfaceswater
April weather nearby: Ko Pha-ngan 27 km · Ko Tao 63 km · Surat Thani 79 km · Tha Kham 91 km · Ban Na San 103 km · Lang Suan 104 km · Nakhon Si Thammarat 123 km · Pak Phanang 135 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 Ko Samui (9.5357°, 99.9357°, elevation 8 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).