Koh Samui Weather and Seasons

A tropical island Koh Samui weather and the climate offers visitors plenty of hot sunny days year round. Throughout the year daytime temperatures average between 28-34°C. There are three seasons hot dry and rainy. Tropical showers are every season some only lasting a few minutes. The sunsets in Koh Samui are stunning and throughout the seasons the sky is a photographers dream.

Koh Samui weather can change very quickly. The guide below is not an accurate weather forecast. For the rest of the world weather patterns are changing. Unexpected storms or heat are not predictable and from our experience in Koh Samui for the last four years, this is a guide only. Rain causes enough problems but fires also damage in the intense heat.

The Seasons

During the rainy season, you can expect local roads to flood. Boat trips will be cancelled depending on the weather. Restaurants beaches and cafes are quieter and accommodation is cheaper at this time of year. In the rainy season, Koh Samui is lush and green. High Season the island is busy. Accommodation and flights are at their peak. The weather and climate are that expected of a tropical paradise. Dry season brings good weather cheaper flights and accommodation. Beaches are not as busy.

Month by Month

January to February –  Middle of January until the end of February the Christmas tourists return home. This is still classed as high season. The weather is still good and the beaches and hotels a little cheaper.

March to May – The hottest months in Koh Samui. Hotel prices are high. Schools are closed the beaches are busy. Vendors struggle to work on the beaches in the heat you may not see many. The winds begin to pick up in May.

April – New Year in Thailand called Songkran. A busy time for hotels and flights. Many of the locals leave the island to spend New Year with family on the mainland.  Flights get booked and are not as cheap. Water fights to celebrate new year take place around the island. A great time to visit and experience the world’s biggest water fight.

June to Aug – The weather and climate are good. Daily sunshine but tropical rain showers can take you by surprise.

September to October –  Unpredictable tropical showers and heavy rain occasionally. Despite the rain generally short burst

November –  Main monsoon month. Accommodation is cheap and the island is quiet preparing for the busy Christmas and New approaching. Unpredictable heavy rain and tropical storms. Local flooding is a regular occurrence. Despite the rain, there is great sunshine too.

December – Christmas and New Year the weather and climate are good. Short tropical storms the rain disappearing as quickly as it arrives. Accommodation is at peak prices and booked months in advanced.

General Information

Check forecasts if you are planning trips around the island. Diving is a gamble underwater visibility decreases by 30% during the monsoon period. Koh Samui weather at night is only a couple of degrees cooler than the day. You won’t need more than a light sweater mainly for air-conditioned buildings. Disposable ponchos are handy to keep in your bag should an unexpected tropical shower occur. You will notice in the rainy season flip flops are still the main footwear. A pair of trainers is handy for the trips and tours especially after the rainy season when the ground is softer.


Jellyfish have been spotted in the waters. In recent years there have been a couple of deaths from boxed jellyfish. If you are stung by a jellyfish seek immediate medical assistance. The rains stir the oceans and currents the jellyfish thrive in these conditions. Follow any warnings on the beach especially after rain. Do not swim even in the shallow waters if the advice is not too.

Rainy Activities

There are many bars restaurants and cafes serving great food. Take some time to explore the temples or indoor markets. Visit the shopping mall Central Festival. Curl up in a Sala with a book and watch the storm. Koh Samui has plenty of activities in the rainy season.