Season by season
Cool & dry season
January is a transition month as the rains tail off. From February to April the weather is dry and settled, the sea is calm and clear, and temperatures are warm rather than oppressive — the most reliable time for Ang Thong and for diving at Sail Rock.
Hot season
May to September is hot and mostly sunny, with brief storms. While the Andaman coast is in monsoon, the Gulf stays largely calm, so July and August are a second high season here, busy with European families. Book boats and rooms early.
Rainy season & sea conditions
The north-east monsoon brings the heaviest rain from October to December, peaking in November, with rough seas, cancelled ferries, occasional flooding and the seasonal closure of Ang Thong. Waterfalls are at their best.
Month by month
| Month | Avg high | Avg low | Rainfall | Crowds |
|---|---|---|---|---|
| January | 29°C | 24°C | 140 mm | Very busy |
| February | 30°C | 25°C | 60 mm | Very busy |
| March | 31°C | 25°C | 80 mm | Busy |
| April | 32°C | 26°C | 80 mm | Busy |
| May | 33°C | 26°C | 150 mm | Busy |
| June | 32°C | 26°C | 110 mm | Busy |
| July | 32°C | 25°C | 120 mm | Very busy |
| August | 32°C | 25°C | 110 mm | Very busy |
| September | 32°C | 25°C | 120 mm | Busy |
| October | 31°C | 24°C | 300 mm | Quiet |
| November | 30°C | 24°C | 500 mm | Quiet |
| December | 29°C | 24°C | 200 mm | Very busy |
Temperatures and rainfall are approximate long-term averages for the nearest weather station; individual years vary, and mountain areas are cooler than the figures shown.
Festivals & events
- Monthly: The Full Moon Party at Haad Rin, with Half Moon and other jungle parties in between.
- April: Songkran, Thai New Year, 13–15 April, celebrated with water fights on both islands.
- May–June: The Samui Regatta, a week of yacht racing off Chaweng.
- July–August: Peak summer season for European visitors.
- November: Loy Krathong at full moon — and usually the wettest weeks of the year.
Our advice
Choose February to April for the best all-round conditions, or June to August if you are travelling in the northern summer, when this is the driest beach region in Thailand. Avoid November if you can. Our seasons guide compares the two coasts month by month.
