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Best time to visit Koh Samui: month by month
Short answer
January to August is the best period, with mostly dry, sunny weather and highs of about 28–31°C; March to May is the hottest. Samui follows the Gulf pattern rather than Phuket's: its rainy season peaks from October to December, when heavy rain and rough seas can cancel boat trips.
Month by month
| Month | High | Low | Rainy days | Crowds |
|---|---|---|---|---|
| Jan | 28°C | 24°C | 18 | high |
| Feb | 28°C | 24°C | 16 | high |
| Mar | 30°C | 25°C | 14 | high |
| Apr | 31°C | 26°C | 18 | high |
| May | 31°C | 26°C | 20 | medium |
| Jun | 31°C | 26°C | 15 | medium |
| Jul | 30°C | 26°C | 21 | high |
| Aug | 31°C | 26°C | 17 | very high |
| Sep | 30°C | 25°C | 22 | medium |
| Oct | 29°C | 25°C | 27 | low |
| Nov | 28°C | 24°C | 27 | low |
| Dec | 28°C | 24°C | 19 | very high |
Temperatures and rainy days: Copernicus ERA5 averages, 2021–2023. Crowd levels are our estimate.
Season by season
Spring (Mar–May)
Hot and fairly dry, with highs of about 30–31°C and the calmest seas; ideal for Ang Thong and Koh Tao trips.
Summer (Jun–Aug)
Highs of about 30–31°C with occasional showers; still good weather while the Andaman coast is rainy. July–August is busy with European holidays.
Autumn (Sep–Nov)
September is changeable; October and November are the wettest months (about 27 rainy days in each), with rough seas.
Winter (Dec–Feb)
December is still rainy early on; January and February dry out with highs of about 28°C and pleasant breezes. Christmas and New Year are peak season.
Events worth planning around
- Songkran Thai New Year water festival (13–15 April)
- Loy Krathong, with floating lanterns and offerings (November, by the lunar calendar)
- Buffalo fighting festivals around Songkran and other holidays
- Full Moon Party on nearby Koh Phangan (monthly)
When to avoid
October to early December brings the heaviest rain and rough seas, with Ang Thong tours sometimes cancelled; Christmas and New Year are the most expensive weeks.
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Common questions
What is the best month to visit Koh Samui?
February to April, with dry weather, highs of about 28–31°C and calm seas.
When is the rainy season on Samui?
Mainly October to December, unlike Phuket, whose rains peak from about May to October.
Is Samui good in July and August?
Yes, the weather is usually good, though it is busy with European summer holidays.