Thailand
Best time to visit Koh Samui
Koh Samui is hot all year, with highs of 29–33°C, so the best time to visit is the drier season: January to April and June. October is the wettest month, with rain on about 21 days.
Koh Samui month by month
From daily weather for 2011–2025. Tap a month for the full picture.
- January29°Beach weatherSea 28° · 6 rainy days
- February29°Beach weatherSea 29° · 4 rainy days
- March31°Beach weatherSea 29° · 4 rainy days
- April32°Beach weatherSea 30° · 7 rainy days
- May33°Very hotWetSea 31° · 12 rainy days
- June33°MildSea 30° · 8 rainy days
- July33°MildSea 30° · 9 rainy days
- August33°MildSea 30° · 9 rainy days
- September32°WetSea 30° · 14 rainy days
- October31°WetSea 30° · 21 rainy days
- November30°WetSea 29° · 19 rainy days
- December30°WetSea 28° · 10 rainy days
Beach weather = highs of 25°C or more and fewer than seven rainy days. Good for sightseeing = highs between 18°C and 28°C and fewer than ten rainy days. Very hot = highs of 33°C or more. Wet = ten or more rainy days. Cool = highs below 18°C. How we measure
Quick answers
- When is the best time to visit Koh Samui?
- Koh Samui is hot all year, with highs of 29–33°C, so the best time to visit is the drier season: January to April and June. October is the wettest month, with rain on about 21 days.
- What is the hottest month in Koh Samui?
- May, with average highs of 33°C and lows of 26°C.
- When is the sea warmest in Koh Samui?
- May, at about 31°C. It is coolest in January, at about 28°C.
- What is the rainiest month in Koh Samui?
- October, with rain on about 21 days and 307 mm in a typical month.