There are only two seasons in this part of Thailand:

• The dry and hot season starts in October-November and ends in May.
• The wet season or monsoon starts from June to October.

The temperature raises with the season. The coolest time is at the beginning of the dry season in October with a low humidity level. The temperature will raise up to May which is normally very dry.
But because of global warming and climate changes, there can be some variations from year to year with small showers during the dry season. Don't worry, anything to spoil your holidays.

During the wet season, it can rain hours non-stop but you can still get sunny days. This is the so-called "low season", with cheaper prices in hotels and resorts and the island running in slow motion and very quietly.

In the middle of the island, in the tropical forest, the humidity level is high almost all year. And because of this rainforest, do not be surprised to see big clouds on top of the island. It doesn't mean that it will rain.
You can see in the morning the humidity rising from the forest and forming small clouds.

Koh Chang has the particularity to have beautiful sunsets. With or without clouds, every evening will look different with amazing colours in the sky.

I'm not a guru and I can't say how will be the weather tomorrow, next week, or next month. The weather can change very fast in Koh Chang, it can even rain in one part and be sunny in the other part of the island. The current weather is displayed below or check the 10-Day Weather Forecast.
Have also a look at the radar rain map over Thailand.