Koh Samui weather in August 2025

Expect 31°C daytime maximum temperatures in the shade with on average 6 hours of sunshine per day in Koh Samui in August. Check more long-term weather averages for Koh Samui in August before you book your next holiday to Thailand in 2025/2026.

31
31°C max day temperature
6
6 hours of sunshine per day
17
17 days with some rainfall
24
24°C min night temperature
12
12 hours of daylight per day
VH
Very High heat & humidity
137
137 mm of monthly rainfall
11
11+ (Extreme) UV index
29
29°C sea temperature

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The August weather guide for Thailand (Koh Samui) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm) | Imperial (°F / inches)

More about Thailand

How hot is it in Koh Samui in August?

Daytime temperatures usually reach 31°C in Koh Samui in August with very high heat and humidity, falling to 24°C at night.

How sunny is it in Koh Samui in August?

There are normally 6 hours of bright sunshine each day in Koh Samui in August - that's 47% of daylight hours.

How warm is the sea around Koh Samui in August?

The average sea temperature around Koh Samui in August is 29°C.

Does it rain in Koh Samui in August?

There are usually 17 days with some rain in Koh Samui in August and the average monthly rainfall is 137mm.

Koh Samui August sunrise & sunset times

Browse the sunrise and sunset times for Koh Samui in August 2025. Select a month to view Koh Samui sunrise and sunset times for the next 12 months.

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

Date	Sunrise times	Sunset times
Friday, 1st August 2025	06:10	18:42
Saturday, 16th August 2025	06:11	18:37
Sunday, 31st August 2025	06:11	18:29

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Thailand - quick facts
Flight time^✝	15 hours
Time difference	UK +7 hours
Language(s)	Thai, Isan
Currency	Thai Baht
Electricity	A + B + C + O plug (230V)
Driving side	Left
Why visit?	Beaches Culture Nature Nightlife
Tourist info	Tourism Authority of Thailand