Weather in Koh Samui
What's the weather like in Koh Samui?
Koh Samui has warm year-round and heavy rainfall, especially in the wet season. Average daytime highs range from 28°C (82°F) in January to 30°C (86°F) in July, with overnight lows around 25°C (76°F) and 26°C (79°F) respectively.
For comfortable sightseeing temperatures (18–26°C daytime highs), the best months to visit Koh Samui are January, and November through December.
Quick facts
- Country
- 🇹🇭 Thailand
- Region
- Asia
- Time zone
- Asia/Bangkok
- Coordinates
- 9.502, 99.965
Monthly climate
Long-run averages for each month of the year.
| Month | Avg high | Avg low | Rainfall | Rain days | Snow days |
|---|---|---|---|---|---|
| January | 28°C / 82°F | 25°C / 76°F | 113 mm | 24 | — |
| February | 28°C / 83°F | 25°C / 77°F | 33 mm | 17 | — |
| March | 30°C / 86°F | 26°C / 78°F | 32 mm | 17 | — |
| April | 31°C / 87°F | 27°C / 80°F | 107 mm | 23 | — |
| May | 31°C / 87°F | 27°C / 80°F | 130 mm | 29 | — |
| June | 30°C / 86°F | 27°C / 80°F | 96 mm | 27 | — |
| July | 30°C / 86°F | 26°C / 79°F | 115 mm | 28 | — |
| August | 30°C / 86°F | 26°C / 79°F | 94 mm | 28 | — |
| September | 29°C / 84°F | 26°C / 78°F | 172 mm | 29 | — |
| October | 28°C / 83°F | 25°C / 77°F | 234 mm | 31 | — |
| November | 28°C / 82°F | 25°C / 77°F | 274 mm | 29 | — |
| December | 28°C / 82°F | 25°C / 76°F | 182 mm | 24 | — |
Koh Samui by month
Detailed weather for any specific month:
Seasonal patterns to know
Southeast Asia rainy season runs May–October. Daily afternoon thunderstorms are typical. Dry season is November–April.
Cities with a similar climate to Koh Samui
Frequently asked questions
When is the best time to visit Koh Samui?
The most comfortable months in Koh Samui are usually February, March, December, when average highs sit near 18–26°C (64–79°F) with relatively little rain. See the full month-by-month breakdown for the exact figures.
What is the hottest month in Koh Samui?
April is typically the hottest month in Koh Samui, averaging a high of 31°C (87°F).
What is the coldest month in Koh Samui?
January is usually the coldest, with average lows around 25°C (76°F).
Does it snow in Koh Samui?
Snow is rare in Koh Samui; the climate data shows essentially no snowfall across the year.
Live forecast, sunrise/sunset, and more.