Koh Samui: monthly weather and climate
Koh Samui · Southern Gulf of Thailand
February is Koh Samui's driest month, with clear weather suited to spending time on the beach. The rainy season lasts from October to December, with particularly heavy rain in November. Temperatures still rise in April despite low rainfall, so compare both rain and temperature if you prefer cooler weather.
Before choosing your travel dates
December is included in the recommended travel period and described as the start of the peak season, but the monthly table rates it as not recommended. These descriptions differ, so December cannot be presented unconditionally as a good month to visit.
The October description says rainfall doubles, but the monthly table records 122 mm in September and 310 mm in October.
When are the dry and rainy seasons?
- Best time to visit
- Dec–Mar
- Dry season
- Jan–Sep
- Rainy season
- Oct–Dec
- Hottest month
- Apr (33°C)
- Wettest month
- Nov (507 mm)
Monthly weather and climate
Compare the table below to see which months are hotter or wetter. These are historical climate averages; they do not provide a forecast for your travel dates or tell you whether swimming will be permitted or safe.
| Month | Travel rating | Temperature | Rainfall | Rainy days | Humidity | Sunshine hours | Sea conditions |
|---|---|---|---|---|---|---|---|
| January | + Good | 24~29°C | 86 mm | 11 days | 80% | 7 hours | Calm |
| February | + Good | 25~29°C | 54 mm | 5 days | 78% | 8 hours | Calm |
| March | + Good | 26~31°C | 81 mm | 4 days | 77% | 8 hours | Calm |
| April | + Good | 26~33°C | 83 mm | 8 days | 77% | 8 hours | Calm |
| May | ± Average | 26~33°C | 156 mm | 16 days | 78% | 7 hours | Moderate |
| June | ± Average | 26~32°C | 124 mm | 15 days | 77% | 6 hours | Moderate |
| July | + Good | 25~32°C | 116 mm | 15 days | 77% | 6 hours | Moderate |
| August | + Good | 25~32°C | 111 mm | 15 days | 78% | 6 hours | Moderate |
| September | ± Average | 25~31°C | 122 mm | 16 days | 79% | 6 hours | Moderate |
| October | - Not recommended | 24~30°C | 310 mm | 20 days | 82% | 5 hours | Rough |
| November | - Not recommended | 24~29°C | 507 mm | 20 days | 85% | 4 hours | Rough |
| December | - Not recommended | 24~30°C | 210 mm | 15 days | 82% | 6 hours | Moderate |
| Month | Weather and travel advice |
|---|---|
| January | This is the coolest month of the year. The weather is warm, with pleasant temperatures. |
| February | This is the driest month, with clear, settled weather suited to spending time on the beach. |
| March | The weather is warm and dry. This is one of the months with relatively pleasant temperatures. |
| April | Temperatures rise, but rainfall remains very low. |
| May | There are many clear days, though rainfall increases as the season progresses. |
| June | Hot weather comes with moderate rainfall, mostly in brief showers. |
| July | Conditions are warm with moderate rainfall, similar to June. |
| August | The weather is slightly more pleasant than in July. Brief showers occur from time to time. |
| September | The temperature range is 25–31°C and rainfall is 122 mm. The rainy season begins in October. |
| October | Cloud cover increases as the rainy season begins. Rainfall rises sharply from 122 mm in September to 310 mm this month. |
| November | The rainy season is short, but rain is heavy this month. This is Koh Samui's wettest month. |
| December | Rain decreases quickly and the weather becomes cooler. The existing weather guidance describes this as the start of the peak tourist season. |