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Koh Samui weather in September 2025
Expect 88°F daytime maximum temperatures in the shade with on average 6 hours of sunshine per day in Koh Samui in September. Check more long-term weather averages for Koh Samui in September before you book your next holiday to Thailand in 2025/2026.
- 8888°F max day temperature
- 6 hours of sunshine per day
- 1717 days with some rainfall
- 7575°F min night temperature
- 1212 hours of daylight per day
- VHVery High heat & humidity
- 5.65.6 inches of monthly rainfall
- 1111+ (Extreme) UV index
- 8484°F sea temperature
More about Koh Samui
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Koh Samui by month
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Recommended for Thailand
The September 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) | Imperial (°F)
More about Thailand
How hot is it in Koh Samui in September?
Daytime temperatures usually reach 88°F in Koh Samui in September with very high heat and humidity, falling to 75°F at night.
How sunny is it in Koh Samui in September?
There are normally 6 hours of bright sunshine each day in Koh Samui in September - that's 47% of daylight hours.
How warm is the sea around Koh Samui in September?
The average sea temperature around Koh Samui in September is 84°F.
Does it rain in Koh Samui in September?
There are usually 17 days with some rain in Koh Samui in September and the average monthly rainfall is 5.6 inches.
Koh Samui September sunrise & sunset times
Browse the sunrise and sunset times for Koh Samui in September 2025. Select a month to view Koh Samui sunrise and sunset times for the next 12 months.
JanFebMarAprMayJunJulAugSepOctNovDec
Date | Sunrise times | Sunset times |
---|---|---|
Monday, 1st September 2025 | 06:11 | 18:29 |
Monday, 15th September 2025 | 06:10 | 18:20 |
Tuesday, 30th September 2025 | 06:08 | 18:11 |
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