Visitors are sometimes incorrectly informed about Koh Samui's seasons prior to their departure. Not everyone is aware for example, that Samui does not have the same rainy season as does Phuket. This is because Koh Samui is situated on the Gulf coast and faces east, and feels the effect of the Northeast monsoon.

January - February is the cool season. Temperatures average a pleasant 79°F, 26°C. This is generally the best time to visit as it is not too hot.

March - May is the hot season, the temperature starts warming up, it has been known to reach 40°C. There is generally less rain during these months.

June - September Generally speaking, between these months, most days will be filled with sun, except for the occasional downpour, which usually doesn't last long.

October - December Frequent showers (not monsoons) come in October, and last until sometime around mid December, when the weather generally clears up with extended periods of dry and often sunny weather. Water sports enthusiasts should note that the sea can get rough at this time, and visibility can be affected.