Weather in Ko Samui - 14-day forecast

Detailed weather forecast for Ko Samui, Thailand: daytime and night temperature, rain, sunrise and sunset - today and for the next two weeks.

Forecast for the next days in Ko Samui

today🌧️ 29°💧 1.3 mm

Thu🌧️ 28°💧 0.6 mm

Fri🌧️ 28°💧 0.6 mm

Sat🌧️ 28°💧 1.9 mm

Sun🌧️ 29°💧 0.9 mm

Mon🌧️ 28°💧 12.4 mm

Tue🌧️ 28°💧 3.8 mm

Wed🌧️ 29°💧 2.6 mm

14-day forecast - Ko Samui

📅 Ko Samui 30 & 45-day weather - long-range outlook

Next 16 days · forecast

29°

around 29° at night · days with rain: 9

Weeks 3-4 · avg for July

32°

around 27° at night · rain chance 45%

Weeks 5-7 · avg for August

33°

around 27° at night · rain chance 39%

The 30 & 45-day outlook for Ko Samui: the next 16 days are a numerical forecast updated daily - on average 29° by day and 29° at night. Further out we rely on multi-year climate averages: around 32° in July, and about 33° in August. Forecasts beyond two weeks are indicative only.

Day-by-day forecast for Ko Samui

Wednesday8 July 2026

🌧️29°light rain

sunrise 06:05 · sunset 18:45 · night 29° · evening 30° · rain 1.3 mm · humidity 77% · wind 8 m/s · clouds 88%

Thursday9 July 2026

🌧️28°light rain

sunrise 06:06 · sunset 18:45 · night 29° · evening 30° · rain 0.56 mm · humidity 77% · wind 9 m/s · clouds 95%

Friday10 July 2026

🌧️28°light rain

sunrise 06:06 · sunset 18:45 · night 28° · evening 30° · rain 0.62 mm · humidity 77% · wind 9 m/s · clouds 99%

Saturday11 July 2026

🌧️28°light rain

sunrise 06:06 · sunset 18:45 · night 29° · evening 29° · rain 1.87 mm · humidity 75% · wind 10 m/s · clouds 100%

Sunday12 July 2026

🌧️29°light rain

sunrise 06:06 · sunset 18:45 · night 29° · evening 29° · rain 0.88 mm · humidity 74% · wind 11 m/s · clouds 97%

Monday13 July 2026

🌧️28°light rain

sunrise 06:07 · sunset 18:45 · night 29° · evening 28° · rain 12.39 mm · humidity 76% · wind 11 m/s · clouds 99%

Tuesday14 July 2026

🌧️28°light rain

sunrise 06:07 · sunset 18:45 · night 28° · evening 28° · rain 3.75 mm · humidity 75% · wind 12 m/s · clouds 100%

Wednesday15 July 2026

🌧️29°light rain

sunrise 06:07 · sunset 18:45 · night 29° · evening 30° · rain 2.55 mm · humidity 73% · wind 10 m/s · clouds 99%

Thursday16 July 2026

🌧️28°light rain

sunrise 06:07 · sunset 18:45 · night 29° · evening 29° · rain 2.07 mm · humidity 71% · wind 9 m/s · clouds 100%

Friday17 July 2026

🌧️29°light rain

sunrise 06:08 · sunset 18:45 · night 29° · evening 29° · rain 0.6 mm · humidity 70% · wind 10 m/s · clouds 100%

Saturday18 July 2026

🌧️30°light rain

sunrise 06:08 · sunset 18:45 · night 29° · evening 29° · rain 0.24 mm · humidity 67% · wind 12 m/s · clouds 99%

Sunday19 July 2026

🌧️30°light rain

sunrise 06:08 · sunset 18:45 · night 28° · evening 29° · rain 1.83 mm · humidity 67% · wind 12 m/s · clouds 100%

Monday20 July 2026

🌧️30°light rain

sunrise 06:08 · sunset 18:45 · night 29° · evening 29° · rain 0.27 mm · humidity 70% · wind 12 m/s · clouds 99%

Tuesday21 July 2026

🌧️30°light rain

sunrise 06:08 · sunset 18:45 · night 29° · evening 30° · rain 0.57 mm · humidity 72% · wind 12 m/s · clouds 48%

Wednesday22 July 2026

🌧️30°moderate rain

sunrise 06:09 · sunset 18:44 · night 29° · evening 29° · rain 6.66 mm · humidity 71% · wind 12 m/s · clouds 61%

Thursday23 July 2026

🌧️29°light rain

sunrise 06:09 · sunset 18:44 · night 29° · evening 29° · rain 2.34 mm · humidity 77% · wind 11 m/s · clouds 100%

☀️ UV index in Ko Samui - is it safe to sunbathe?

Today the UV index in Ko Samui is 9 (very high) - unprotected fair skin can burn in about 25 minutes. SPF 50, long sleeves and shade between 10:00 and 16:00.

🌊 Sea temperature - Ko Samui

Water today

31°C

Week avg

31°C

Waves today

0.3 m

How's the water?

very warm

16-day sea temperature forecast:

8.07 31°C9.07 31°C10.07 31°C11.07 31°C12.07 31°C13.07 30°C14.07 31°C15.07 31°C16.07 31°C

Average sea temperature through the year:

Jan 29°CFeb 29°CMar 30°CApr 32°CMay 32°CJun 31°CJul 31°CAug 31°CSep 30°COct 31°CNov 30°CDec 29°C

Sea-surface temperature from marine models, updated daily. See also: where the sea is warmest right now.

Air quality and smog in Ko Samui

City	PM2.5 (µg/m³)	PM10 (µg/m³)	Air quality
Khlong Luang	31.1	34.3	good
Pak Kret	29.6	33.4	good
Nakhon Ratczasima	13.2	16.9	good
Bangkok	12.8	15.8	very good
Cziang Maj	11.1	14.4	very good
Chon Buri	4	5.5	very good

Based on PM2.5 thresholds. Station readings, updated daily (last reading: 2026-07-08, 08:00).

Ko Samui weather through the year

Warmest, driest months on average: January, February, December.

FAQ - Ko Samui weather

What is the weather like in Ko Samui today?

Today it is about 29° during the day and 29° at night, light rain.

How far ahead can I check the forecast for Ko Samui?

This page shows a detailed 14-day forecast plus the long-term monthly climate, so you can plan both a short trip and a holiday months ahead.