The climate on Koh Samui is very pleasant all year round, with temperatures varying between 25 and 35 degrees Celsius.
There are three seasons:
WARM AND DRY season from February until May
RAINY season from the end of September until November
COOL season which spans from October to January
From February until October, the average temperature is between 32 to 38 degrees, with July to September having some showers, but only for a few hours. This rainy season often amounts to some very refreshing showers before the return of the sunshine.
The climate is tropical and humid all year round, though Koh Samui remains always refreshed by a pleasant sea breeze blowing from the Gulf of Thailand.