Koh Samui Weather Guide - Thailand

Koh Samui is part of Thailand but its weather is somewhat different. Afterall, most of Thailand is part of the Asian land mass and is quite a bit farther north than Koh Samui. Also, the Koh Samui's weather is somewhat different than that of many other southern islands such as Phuket.

While Phuket and many other islands are to the west of the Thai mainland, Koh Samui is to the east, and this does affect its weather. While The easternmost islands are strongly effected by the Indian Ocean, the Thai land mass, although narrow, is mountainous and mitigates this influence on Koh Samui, which is much more effected by the Pacific currents.

The overall climate of Koh Samui is tropical. Both the temperature and the humidity are high all throughout the year. The temperature averages around 30 degrees Celsius or 86 degrees Fahrenheit, which is actually pretty pleasant. Although the temperature does vary according to the time of the year, as does the amount of rainfall.

Generally speaking, there are three seasons on Koh Samui: the dry season, which runs from December through February, the hot season, which goes from March through August, and the rainy season, which goes from September through November. The names of the seasons, however, are a little misleading or inadequate at giving a complete description of what actually happens.

Dry Season

December through February: this is a period of relatively little rain, although it does occur, especially in December. Winds and breezes blow in from the ocean during this time, helping to make this, at least marginally, the least hot time of the year, especially at night. The water is also a degree or two cooler than at other times of the year, but swimming is still pleasant. Because of the winds, this is usually the best time for wind-based water sports

Hot Season

March through August: During much of this time the weather is hot AND dry, especially in March and April. Beginning in May, it begins to rain more frequently. Most of the rain, however, occurs in the form of relatively short showers, usually no more than 20 to 60 minutes in length. It is the hottest time of the year, as the name implies. At least March and April, anyway. At this time, it is at least two or three degrees hotter than at other times of the year.

Rainy Season

September through November: This time of the year also called the monsoon season. During this time, the amount of rainfall the island receives does pick up significantly and gets quite heavy in November. The rains can be quite heavy and last for several hours. However, there are almost always many days when it doesn't rain at all. During the day, the temperatures average 31 degrees Celsius during the day and 24 degrees at night, making this time of the year less hot than "hot" season.

Advice for Travelers - Best Time to Visit

Relatively speaking, the variations in climate on Koh Samui Island are small. If one likes tropical weather, then most times of the year are suitable for visiting. The exception to this would be the time period during October and November. During this time, rainfall can be quite heavy. This is a problem on Koh Samui Island because of overdevelopment and deforestation, and because the terraine is hilly.

In many places the hills coming right down to the beaches. Some parts of the island can suffer severely due to the rains from flooding and mud slides. Among the hardest hit places is Chaweng Beach. While the rains are not life threatening they can be a problem for children and pets. They can also disrupt travel plans.

During this time, one must always dress and plan with the rains in mind, being sure to carry shoes suitable for wading in deep waters. One must also be aware that the rains can disturb what remains of the island's wildlife.

Animals such as snakes can be driven out of their remote living places and forced into places where travelers are. For these reasons, travelers might want to consider visiting Koh Saumi during some other time of the year.