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°C maximum daytime temperature in August in Koh Samui31
    31°C max day temperature
  • 6 hours of sunshine per day
  • 17 days with some rainfall in August in Koh Samui17
    17 days with some rainfall
  • 24°C minimum night-time temperature in August in Koh Samui24
    24°C min night temperature
  • 12 hours of daylight per day in August in Koh Samui12
    12 hours of daylight per day
  • Very high heat & humidity in August in Koh SamuiVH
    Very High heat & humidity
  • 137 mm monthly rainfall in August in Koh Samui137
    137 mm of monthly rainfall
  • UV (maximum) index 11+ (Extreme) in August in Koh Samui11
    11+ (Extreme) UV index
  • 29°C sea temperature in August in Koh Samui29
    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)

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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.

JanFebMarAprMayJunJulAugSepOctNovDec

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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