Koh Samui Weather & Climate: Best Time to Visit

The climate in Koh Samui remains fairly constant, offering comfortable temperatures throughout the year. Average daytime temperatures reach a very warm 31°C (88°F) in May. In January, the coolest month of the year, temperatures drop to a comfortable 29°C (84°F).

At night, temperatures range from around 28°C (82°F) in May to 26°C (79°F) in January.

Check out our detailed temperature page for more information.

Temperature ranges by month

Koh Samui is known for its substantial rainfall, with annual precipitation reaching 1645 mm (65 in). Koh Samui can be quite wet during October, receiving approximately 296 mm (12 in) of precipitation over 20 rainy days.

In contrast, during the driest month (February), you will experience much drier conditions, with 44 mm (1.7 in) of precipitation spread across 5 rainy days. For more details, please visit our Koh Samui Precipitation page.

The mean monthly precipitation over the year, including rain, hail, and snow

The average number of days each month with precipitation

Koh Samui can be enjoyed more throughout the sunniest month of March under a blue sky, with approximately 8.0 hours of sunshine daily. In contrast, the city experiences much darker days in September, with only 4.8 hours of sunlight per day.

Visit our detailed sunshine hours page for more information.

Monthly hours of sunshine

Daily hours of sunshine

The mean water temperature over the year ranges from 27°C (81°F) in January to 30°C (86°F) in April.

Water temperature over the year

The city experiences its highest humidity in October, reaching 85%. In June, the humidity drops to its lowest level at 78%. What does this mean? Read our detailed page on humidity levels for further details.

Relative humidity over the year