Koh Samui monthly weather and climate
Koh Samui · Southern Gulf of Thailand
February is Koh Samui's driest month, with clear weather for spending time at the beach. The rainy season runs from October through December, with particularly heavy rain in November. Temperatures rise even in relatively dry April, so compare both rainfall and temperature if you want a cooler time to visit.
Before choosing your travel dates
December is included in the suggested travel period and described as the start of the busy tourist season, but the monthly table rates it as not recommended. With these conflicting descriptions, December cannot be presented unconditionally as a good month to visit.
The source's October notes say rainfall doubles, but the monthly table shows 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
Use the table below to compare hotter and rainier months. These are historical climate averages, not a forecast for your travel dates or an indication that swimming is allowed or safe.
| Month | Travel rating | Temperature | Rainfall | Rainy days | Humidity | Sunshine | Sea conditions |
|---|---|---|---|---|---|---|---|
| January | + Good | 24~29°C (75.2~84.2°F) | 86 mm | 11 days | 80% | 7 hours | Calm |
| February | + Good | 25~29°C (77~84.2°F) | 54 mm | 5 days | 78% | 8 hours | Calm |
| March | + Good | 26~31°C (78.8~87.8°F) | 81 mm | 4 days | 77% | 8 hours | Calm |
| April | + Good | 26~33°C (78.8~91.4°F) | 83 mm | 8 days | 77% | 8 hours | Calm |
| May | ± Average | 26~33°C (78.8~91.4°F) | 156 mm | 16 days | 78% | 7 hours | Moderate |
| June | ± Average | 26~32°C (78.8~89.6°F) | 124 mm | 15 days | 77% | 6 hours | Moderate |
| July | + Good | 25~32°C (77~89.6°F) | 116 mm | 15 days | 77% | 6 hours | Moderate |
| August | + Good | 25~32°C (77~89.6°F) | 111 mm | 15 days | 78% | 6 hours | Moderate |
| September | ± Average | 25~31°C (77~87.8°F) | 122 mm | 16 days | 79% | 6 hours | Moderate |
| October | - Not recommended | 24~30°C (75.2~86°F) | 310 mm | 20 days | 82% | 5 hours | Rough |
| November | - Not recommended | 24~29°C (75.2~84.2°F) | 507 mm | 20 days | 85% | 4 hours | Rough |
| December | - Not recommended | 24~30°C (75.2~86°F) | 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 comfortable temperatures. |
| February | The driest month brings clear, calm weather for spending time at the beach. |
| March | The weather is warm and dry. This is one of the months with relatively comfortable temperatures. |
| April | Temperatures rise, but there is still very little rain. |
| May | There are plenty of clear days, although rainfall increases as the season progresses. |
| June | The weather is hot, with moderate rainfall, mostly in brief showers. |
| July | As in June, the weather is warm with moderate rainfall. |
| August | Conditions are a little more comfortable than in July. Occasional brief showers pass through. |
| September | Temperatures range from 25–31°C, and rainfall totals 122 mm. The rainy season starts in October. |
| October | Skies become cloudier as the rainy season begins. Rainfall rises sharply from September's 122 mm to 310 mm this month. |
| November | The rainy season is short, but this month brings heavy rain. It is Koh Samui's wettest month. |
| December | Rain decreases quickly and temperatures cool. The source's weather notes describe this as the start of the busy tourist season. |