Koh Samui, located in the Gulf of Thailand just north of Koh Phangan, has a unique weather pattern that’s slightly different from other Thai islands. It features a distinct rainy season peaking in November, a long sunny season from December to April, and a generally warm, tropical climate year-round. While it shares similarities with Koh Phangan, Samui’s rainfall can sometimes extend later into December, and its size means microclimates exist across the island.
The skies clear after the monsoon, humidity drops, and this becomes the peak beach season. January to March is the most reliable stretch for sunshine, with calm seas perfect for snorkeling and diving.
Temperatures rise and humidity climbs. Quick showers may start in late April, but most days remain hot and bright. April is especially lively with Songkran celebrations.
Expect a mix of sunshine and tropical downpours. These months still offer good beach days, especially July–August, when Samui remains a popular summer escape in Thailand.
November brings the heaviest rainfall, with frequent storms and occasional flooding in low-lying areas. Seas can be rough, and ferry services are sometimes disrupted. By late December, conditions typically improve quickly.
Here’s what you can expect month by month:
October–November is the peak rainy period, sometimes stretching into early December.
February is the clearest and driest, with January–March being reliably sunny as well.
The water stays a pleasant 28–30 °C all year, ideal for swimming and snorkeling.
Yes. Though there are occasional showers, Koh Samui is one of Thailand’s better islands for summer holidays with plenty of sunny days.
Mostly during October–November, when rough seas can delay or cancel services. Allow flexibility in your schedule if traveling at this time.
Keep updated with phanganist.com by following our Facebook page.
Your trusted travel tools in one place
