Koh Samui has a warm, tropical climate that makes it a great destination year round. Like all of Thailand’s islands, Koh Samui has three seasons: the cool season, the hot season, and the rainy season, all of which last for three to five months.
Koh Samui © webdesignsamui
- The cool season, which lasts from mid-December until February, is the most popular time to visit Koh Samui. One significant advantage of Koh Samui is that it has the shortest rainy season of any Thai island, which lasts for just two months towards the end of the year.
- Relative humidity on Koh Samui is consistently between 75 and 85 per cent throughout the year, with the highest humidity in the October-November rainy season. Most beaches on Koh Samui get calm winds throughout the year, making the island’s high humidity less noticeable.
- Although Samui’s weather can vary from month to month, it’s possible to enjoy your holiday on Koh Samui no matter when you visit. Below, we’ve provided month-by-month overviews of the weather on Koh Samui to help you choose the right timing for your trip.
- Note: We’ve included the average number of rainy days for each month below. A rainy day, in the context of this guide, refers to any day with some rainfall. Since most rainy days on Koh Samui only have 30-60 minutes of actual showers, don’t let a rainy month put you off visiting. The only truly rainy months on Koh Samui are October, November and early December.
Recommended Koh Samui Hotels
Best Time to Visit Koh Samui
- From a weather perspective, the best time to visit Koh Samui is from late December until early March. This is the coolest and driest period of the year, with very little rainfall and comfortable temperatures of 25.0 to 30.6°C.
- Almost all of Koh Samui’s major roads are concrete, making it easy to get around the island in the wet season. Visiting after the end of March allows you to take advantage of lower prices for accommodation and many attractions due to the smaller number of tourists.
- Koh Samui is a good holiday destination even during the early wet season. Rainfall is usually limited to the late afternoon with only a few full days of rain, allowing you to enjoy the beaches before the monsoon rain arrives for the day.
Weather in Koh Samui in January
- January is a warm, dry month on Koh Samui. The average rainfall for the month is just 86.2mm, with an average of 11 rainy days. An average daily high temperature of 29.0°C makes January a pleasant month on Koh Samui that’s neither too hot nor too cool.
Weather in Koh Samui in February
- Weather in February on Koh Samui is much the same as January. February is the driest month of the year, with just 54.4mm of rainfall and five rainy days on average. The average daily high temperature is 29.4°C, with average lows of 25.0°C.
Weather in Koh Samui in March
- March is another warm, dry month on Koh Samui. During March, Samui gets an average of 80.8 millimetres of rainfall, with four rainy days. Average temperatures sit between a high of 30.6 and a low of 25.6°C, making March one of the most comfortable months to spend on Koh Samui.
- The low season on Koh Samui begins in March, with most of the high season tourists returning home and hotel room availability increasing. From March to October, prices on Koh Samui are low, with smaller crowds on the beaches.
Weather in Koh Samui in April
- Temperatures begin to increase on Koh Samui in April. The average daily high is 32.6°C, with average lows of 26.1°C. Rainfall remains low at just 83.1mm for the month, with an average of eight rainy days.
Weather in Koh Samui in May
- Koh Samui’s summer weather kicks into full gear in May. Average highs reach 32.5°C, with an average low of 25.7°C. May is an extremely sunny month for Koh Samui, although rainfall also begins to increase, with 155.9mm of rain and an average of 16 rainy days.
Weather in Koh Samui in June
- June is another very hot month on Koh Samui. The average high temperature is 32.2°C for the month, with average lows of 25.5°C. June gets a moderate amount of rain, with 124.1mm and an average of 15 days featuring rain showers.
Weather in Koh Samui in July
- Weather in July on Koh Samui is much the same as June, with 15 days featuring showers and an average of 116.3mm of rain throughout the month. Temperatures vary between an average high of 32.1°C and an average low of 25.2°C.
Weather in Koh Samui in August
- August on Koh Samui is hot but more comfortable than July, with average highs of 31.7°C and average lows of 25.2°C. Koh Samui gets an average of 15 rainy days and 110.9mm of rainfall in total during August.
Weather in Koh Samui in September
- September is the final dry month of the year before Koh Samui’s rainy season begins, with just 121.7mm of rainfall and an average of 16 rainy days. Temperatures range from a high of 30.5°C to an average low of 24.8°C, with plenty of sunshine.
Weather in Koh Samui in October
- Koh Samui’s short rainy season begins in October. Total rainfall more than doubles from the last month, to an average of 309.8mm for the month. There are 20 rainy days on average in October on Koh Samui, with average highs of 29.6°C and lows of 24.3°C.
Weather in Koh Samui in November
- November marks the peak of Koh Samui’s rainy season, with 506.6mm of rain throughout the month, 20 rainy days on average and 85% humidity. Despite the rain, temperatures remain on the warm side, with average highs of 29.2°C and lows of 24.1°C.
- The rainy season comes to an end in the last weeks of November or first weeks of December, making the end of the month a good time to visit Koh Samui before the large crowds of tourists arrive at the beginning of high season.
Weather in Koh Samui in December
- December is the beginning of high season on Koh Samui, with far less rain than November and cool, comfortable weather. On average, there is 210.3mm of rainfall in December, with 15 rainy days and 82% humidity. Average temperatures range from 32.0°C to 23.9°C.
Things To Do On Koh Samui
From diving to ziplining, spa treatments, golf and more, Koh Samui has a huge range of unique and exciting activities for visitors. Learn about the best things to do on Koh Samui, whether you feel like a relaxing day or an intrepid adventure.
Buy Ferry Tickets To Koh Samui
You can buy bus and ferry tickets to Koh Samui online. Use the search box below to find out departure times, prices and to book online. Enter a different starting point if you’re not coming from Bangkok
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