Koh Samui Weather

Climate and Best Time to Visit Koh Samui

Gulf of Thailand Weather
Andaman Sea Weather

The weather in the Gulf of Thailand (east coast of Thailand: Koh Samui, Koh Phangan and Koh Tao) is quite different from the weather in the Andaman Sea (west coast of Thailand: Phuket, Krabi and Koh Lanta). Although the temperature ranges from 23 °C to 32 °C all year around in both the Andaman Sea and the Gulf of Thailand, there are important differences in precipitation. The best time to visit Phuket and Krabi, is not necessarily the best time to visit Koh Samui. Comparing the weather in Koh Samui and Phuket, average rainfall shows November is the rainiest month in Koh Samui; September in Phuket.

Check the graphs below comparing rainfall in different popular destinations in Thailand. The data is provided by the Thai Meteorological Department (2018).

Koh Samui Weather by Season​

Koh Samui is a tropical island with pleasant temperatures all year round. Rain can be unpredictable and, at times, torrential. There are 3 seasons in Koh Samui as in the rest of Thailand: Dry, Hot and Rainy, also known as Cool, Hot and Wet.

Best Time to Visit Koh Samui

The best time to visit Koh Samui is different for everyone, and it depends on what is more important to you: warm weather and plenty of sunshine, no rain, great prices and offers, avoiding crowds.

November is the wettest month of the year with rainfall on most days. Some holidaymakers, looking to relax, choose this time of year to come and enjoy activities like yoga classes, Muay Thai classes, wellness and fitness retreats. You can take advantage of the quiet beaches and hotel’s lower rates. However, if you are coming from a country with cold or rainy conditions, looking for sun and water sports, probably better to skip the rainy season and visit from mid-December to August.

As we mentioned above, the best time to visit the island depends on your own preferences. If a beach holiday is what you’re after, aim for the hot and dry seasons. If you are into kite surfing, there are some good spots with decent wind speed in Nathon, where you can surf during the quieter months. If you prefer to enjoy a retreat, any time is good. If you are tight on budget, perhaps the low season can be more appealing to your needs.

The best thing about Koh Samui is that you have so many options to choose from, whether you are looking for a beach day, adventure, water sports, exploring, eating or relaxing.

At anytime during the year, including the monsoon season, the average temperature ranges from 28 °C to 30 °C. At night, it might be cooler if there is wind or a little rain, but the daytime temperature is mostly pleasant. Sometimes, in the hot season, rainy days are a blessing!