The weather in Koh Samui is pleasant all year round with average temperature from 26 to 30 degrees centigrade.
Samui monthly Highs & Lows in Centigrade
During the high season, from December to February, the temperature on Samui averages 29 degrees centigrade in the day and 24 degrees at night. Short tropical downpours can still occur in December following the rainy season in October/November. This period is considered the best season for Europeans to visit as the weather in Samui is cooler than later in the year.
Samui Average Daily Hours of Sunshine
From March to June the weather can get hot on Samui with occasional days in the high 30’s and there is not much rain during these months. This is the time of the Songkran festival which is the Thai New Year. The main and most open celebration of Songkran is the throwing of water, people roam the streets with containers of water or water guns, or post themselves at the side of roads with a garden hose and drench each other and passersby. This, however, was not always the main activity of this festival. Songkran was traditionally a time to visit and pay respects to elders, including family members, friends and neighbors. The sea remains calm and low tides can lead to very shallow waters on the island’s beaches. The wind picks up again in May, and this is a popular time for off-season visits.
The weather on Samui during July to September is slightly cooler, with a mini monsoon season that brings occasional storms and periods of heavy rain. These are also popular months for European visitors who take their holidays in July and August. Despite a bit of rain one can be guaranteed plenty of sunshine.
October and November are the wettest months of the year, although even then it doesn't normally fall every day. Unlike many other parts of the country Koh Samui doesn’t have a prolonged or predictable rainy season. During the wettest periods there are rarely more for than two or three days without sun, even during November, which commonly considered to be the monsoon.