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Ko Samui climate: when to go to Ko Samui

Ko Samui is an island located in the Gulf of Siam, in the south-eastern part of Thailand at about 9 degrees north of the equator. The island has a tropical monsoon climate, characterized by stable temperatures in all seasons with variations of a few degrees between the coldest and the warmest, and that can be divided into a rainy season and a dry season.

The short dry season runs from February to April, while the wettest months are between October and December, during the rest of the year rains fall every day, but only for a few tens of minutes, on average, on the island falling almost 2,000 mm of rain per year.

The climate is hot and humid, the average maximum temperatures vary between 29°C and 32°C, while the average minimum temperatures vary between 24°C and 26°C.

The temperature of the sea water is excellent for swimming all year round.


The best time for a trip to Ko Samui are the driest months between February and April, but the months between January and September are also good, considering that at this time it rains usually only for a few tens of minutes each day.

Ko Samui

Ang Thong National Park


KO SAMUI (3 metres)
Month Average low (°C) Average high (°C) Precip. (mm) Precip. days
January 24,2 29,0 86,2  11,0
February 25,0 29,4 54,4  5,6
March 25,6 30,6 80,8  5,9
April 26,1 32,0 83,1  8,6
May 25,7 32,6 155,9  15,6
June 25,5 32,5 124,1  13,7
July 25,1 32,2 116,3  14,4
August 25,2 32,1 110,9  15,2
September 24,8 31,7 121,7  16,2
October 24,3 30,5 309,8  19,6
November 24,1 29,6 506,6  19,2
December 23,9 29,2 210,3  13,7
YEAR 25,0 31,0 1960,1  158,7

Month Sea Water Temperature °C
January 28
February 29
March 29
April 30
May 30
June 30
July 29
August 29
September 29
October 29
November 29
December 28

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