Ko Samui is a beautiful island off the coast of Thailand, near Phuket. Because it’s located in the Gulf of Thailand, the Ko Samui weather is quite different from Phuket weather, even though are quite close geographically.

Ko Samui has three distinct seasons:

  • a dry season that starts in December and goes through to February, where it hardly rains at all and the skies are clear and blue. There is also usually a nice sea breeze blowing during the dry season and you can expect a temperature range of between 22-24 degrees C overnight and around 31-32 degrees C during the day. Perfect beach weather.
  • a hot season that runs from March until August, where there is still almost no rain but the days get quite a bit hotter. Accommodation rates drop a bit during the hot season so it’s not a bad time to visit if you can handle overnight temperatures around 27-28 degrees C and daytime temperatures up around 33-36 degrees C. The water is a bit warmer too during the hot season, around 28 degrees C.
  • a rainy season that goes from September to November, when Ko Samui gets most of its annual rainfall. But we’ve holidayed in Ko Samui during the wet season and it’s really not so bad. During a full week on the island in November, as mentioned in our Ko Samui travel guide, we got rained on twice although we were out and about on a scooter every day. The rain can be quite heavy but not for very long, and it’s not unwelcome because it’s pretty humid and even with some cloud cover the daytime temperatures are still around 31-32 degrees C, usually with a nice sea breeze.

Ko Phangan, which is just north of Ko Samui, has a very similar climate. so if you’re heading there for the full moon party you can use this guide to check the weather forecast.