Koh Samui weather in May 2025

Expect 32°C daytime maximum temperatures in the shade with on average 6 hours of sunshine per day in Koh Samui in May. Check more long-term weather averages for Koh Samui in May before you book your next holiday to Thailand in 2025/2026.

  • 32°C maximum daytime temperature in May in Koh Samui32
    32°C max day temperature
  • 6 hours of sunshine per day
  • 17 days with some rainfall in May in Koh Samui17
    17 days with some rainfall
  • 25°C minimum night-time temperature in May in Koh Samui25
    25°C min night temperature
  • 13 hours of daylight per day in May in Koh Samui13
    13 hours of daylight per day
  • Very high heat & humidity in May in Koh SamuiVH
    Very High heat & humidity
  • 172 mm monthly rainfall in May in Koh Samui172
    172 mm of monthly rainfall
  • UV (maximum) index 11+ (Extreme) in May in Koh Samui11
    11+ (Extreme) UV index
  • 30°C sea temperature in May in Koh Samui30
    30°C sea temperature

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The May 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 May?

Daytime temperatures usually reach 32°C in Koh Samui in May with very high heat and humidity, falling to 25°C at night.

How sunny is it in Koh Samui in May?

There are normally 6 hours of bright sunshine each day in Koh Samui in May - that's 51% of daylight hours.

How warm is the sea around Koh Samui in May?

The average sea temperature around Koh Samui in May is 30°C.

Does it rain in Koh Samui in May?

There are usually 17 days with some rain in Koh Samui in May and the average monthly rainfall is 172mm.

Koh Samui May sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Thursday, 1st May 2025 06:03 18:31
Friday, 16th May 2025 05:59 18:33
Saturday, 31st May 2025 05:58 18:37

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