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 runs from October to December, with particularly heavy rain in November. Temperatures rise in April despite low rainfall, so compare heat and rainfall if you prefer cooler conditions.
Before choosing your travel dates
December is included in the recommended travel period and described as the start of the high season, but the monthly table rates it as not recommended. These accounts differ, so December cannot be described unconditionally as a good month to visit.
The October commentary says rainfall doubles, but the monthly table gives 122 mm for September and 310 mm for 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 hotter and wetter months in the table below. These are historical climate averages: they are not a forecast for your travel dates and do not tell you whether swimming will be possible.
| Month | Travel rating | Temperature | Rainfall | Rainy days | Humidity | Sunshine | Sea conditions |
|---|---|---|---|---|---|---|---|
| January | + Good | 24~29°C | 86 mm | 11 d | 80% | 7 h | Calm |
| February | + Good | 25~29°C | 54 mm | 5 d | 78% | 8 h | Calm |
| March | + Good | 26~31°C | 81 mm | 4 d | 77% | 8 h | Calm |
| April | + Good | 26~33°C | 83 mm | 8 d | 77% | 8 h | Calm |
| May | ± Average | 26~33°C | 156 mm | 16 d | 78% | 7 h | Moderate |
| June | ± Average | 26~32°C | 124 mm | 15 d | 77% | 6 h | Moderate |
| July | + Good | 25~32°C | 116 mm | 15 d | 77% | 6 h | Moderate |
| August | + Good | 25~32°C | 111 mm | 15 d | 78% | 6 h | Moderate |
| September | ± Average | 25~31°C | 122 mm | 16 d | 79% | 6 h | Moderate |
| October | - Not recommended | 24~30°C | 310 mm | 20 d | 82% | 5 h | Rough |
| November | - Not recommended | 24~29°C | 507 mm | 20 d | 85% | 4 h | Rough |
| December | - Not recommended | 24~30°C | 210 mm | 15 d | 82% | 6 h | Moderate |
| Month | Weather and travel advice |
|---|---|
| January | This is the coolest month of the year. It remains warm, but temperatures are pleasant. |
| February | This is the driest period, with clear skies and settled weather for time on the beach. |
| March | The weather is warm and dry, with relatively comfortable temperatures. |
| April | Temperatures rise, while rain remains scarce. |
| May | There are many clear days, but rainfall increases as the season progresses. |
| June | The weather is hot with moderate rainfall, mostly in short showers. |
| July | Conditions are similar to June: warm, with moderate rainfall. |
| August | Conditions are slightly more pleasant than in July, with occasional short showers. |
| September | Temperatures range from 25 to 31°C, with 122 mm of rainfall. The rainy season starts 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 brings heavy rain this month. November is Koh Samui's wettest month. |
| December | Rain decreases rapidly and temperatures become cooler. The existing weather commentary lists this as the start of the tourism high season. |