Island in Surat Thani, Thailand
Koh Samui weather by month and the best time to visit
When to go to Koh Samui
Jan–Aug is mostly dry, Feb–Apr calmest. Heaviest rain and flooding Oct–Dec. Peak crowds and prices in Dec–Jan and Jul–Aug.
Koh Samui weather by month
Average daily high, rainfall and conditions.
- Jan28°135 mm
- Feb28°38 mm
- Mar29°114 mm
- Apr30°90 mm
- May30°170 mm
- Jun30°167 mm
- Jul29°166 mm
- Aug29°144 mm
- Sep29°181 mm
- Oct28°246 mm
- Nov28°375 mm
- Dec28°262 mm
Monthly averages
| Month | High | Low | Rain | Humidity | Conditions |
|---|---|---|---|---|---|
| January | 28°C82°F | 26°C79°F | 135 mm | 80% | Pleasant |
| February | 28°C82°F | 26°C80°F | 38 mm | 79% | Pleasant |
| March | 29°C84°F | 27°C81°F | 114 mm | 78% | Pleasant |
| April | 30°C86°F | 28°C83°F | 90 mm | 77% | Pleasant |
| May | 30°C86°F | 28°C83°F | 170 mm | 78% | Rainy |
| June | 30°C85°F | 28°C82°F | 167 mm | 80% | Rainy |
| July | 29°C84°F | 28°C82°F | 166 mm | 80% | Rainy |
| August | 29°C84°F | 27°C81°F | 144 mm | 81% | Pleasant |
| September | 29°C84°F | 27°C81°F | 181 mm | 81% | Rainy |
| October | 28°C83°F | 27°C81°F | 246 mm | 81% | Rainy |
| November | 28°C83°F | 27°C81°F | 375 mm | 81% | Very wet |
| December | 28°C82°F | 27°C80°F | 262 mm | 80% | Rainy |
Best months across Thailand
| Place | Best months | Warmest month |
|---|---|---|
| Bangkok | Nov–Feb | Mar (36°C) |
| Phuket | Nov–Mar | Mar (30°C) |
| Chiang Mai | Nov–Jan | Apr (37°C) |
| Koh Samui | Jan–Apr, Jul–Aug | May (30°C) |
| Krabi | Nov–Mar | Mar (31°C) |
| Koh Phi Phi | Nov–Mar | Apr (30°C) |
| Koh Phangan | Jan–Apr, Jul–Aug | May (27°C) |
| Pai | Nov–Feb | Apr (35°C) |
| Pattaya | Nov–Feb | Apr (31°C) |
| Koh Tao | Feb–Aug | May (29°C) |
| Patong | Nov–Apr | Mar (30°C) |
| Hua Hin | Nov–Mar | Apr (33°C) |
| Chiang Rai | Nov–Feb | Apr (35°C) |
| Ayutthaya | Nov–Feb | Mar (37°C) |
| Koh Lanta | Nov–Apr | Apr (29°C) |
| Railay | Nov–Mar | Mar (31°C) |
| Kanchanaburi | Nov–Feb | Apr (37°C) |
| Koh Chang | Nov–Feb | Apr (30°C) |
| Khao Lak | Nov–Mar | Mar (31°C) |
| Koh Samet | Nov–Mar | Apr (30°C) |
| Koh Lipe | Nov–Mar | Apr (30°C) |
| Khao Yai | Nov–Feb | Apr (34°C) |
| Khao Sok | Dec–Apr | Apr (32°C) |
| Sukhothai | Nov–Feb | Apr (38°C) |
| Hat Yai | Jan–Apr | Apr (31°C) |
| Kata Beach | Nov–Mar | Mar (30°C) |
| Jomtien | Nov–Feb | Apr (31°C) |
| Rawai | Nov–Mar | Mar (30°C) |
| Udon Thani | Nov–Feb | Apr (37°C) |
| Koh Kood | Nov–Mar | May (30°C) |
Quick answers
What is the best month to visit Koh Samui?
Jan–Apr, Jul–Aug. Jan–Aug is mostly dry, Feb–Apr calmest. Heaviest rain and flooding Oct–Dec. Peak crowds and prices in Dec–Jan and Jul–Aug.
When is the rainy season in Koh Samui?
Rain peaks in November with about 375 mm. Months with 150 mm or more: May–Jul, Sep–Dec.
What is the hottest month in Koh Samui?
May, with average highs of 30°C (86°F).
How cold does Koh Samui get?
The coolest nights are in January, averaging 26°C (79°F).
More about Koh Samui
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Sources
- NASA POWER climatology (2001–2020)
- Bangkok Hospital Samui
- Lomprayah ferries
- Seatran Discovery ferries
- Raja Ferry
- Grab Thailand service areas
Climate averages are modelled from NASA POWER (MERRA-2) for 2001–2020 at about 50 km resolution, so coasts and valleys can differ a little. Compiled and reviewed by SoloSquare. How we compile and score this. Spotted something out of date? Tell us.