Koh Samui monthly weather and climate
Koh Samui · Southern Gulf of Thailand
February is Koh Samui's driest month, with clear weather suited to time on the beach. The rainy season lasts from October to December, with particularly heavy rain in November. Even the relatively dry month of April brings rising temperatures, so compare rainfall and temperature together 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 accounts differ, so December cannot be described unreservedly as a good month to visit.
The October description 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
Use the table below to compare hotter and wetter months. These are historical climate averages, so they do not give a forecast for your travel dates or tell you whether you will be able to swim.
| Month | Travel rating | Temperature | Rainfall | Rainy days | Humidity | Sunshine | 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. Temperatures are warm but pleasant. |
| February | This is the driest, clearest period. Calm weather makes it a good time to spend on the beach. |
| March | It is warm and dry. This is one of the months with relatively pleasant temperatures. |
| April | Temperatures rise, but there is still very little rain. |
| May | There are plenty of sunny days, though rainfall increases as the season progresses. |
| June | Hot weather brings moderate rainfall, mostly in short showers. |
| July | Conditions are similar to June, with warm weather and moderate rainfall. |
| August | It is slightly more pleasant than July, with occasional short showers. |
| September | Temperatures range from 25–31°C, with 122 mm of rainfall. 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 this month brings heavy rainfall. It is Koh Samui's wettest month. |
| December | Rainfall decreases quickly and temperatures become cooler. The existing weather description marks this as the start of the peak tourist season. |