Home › Weather › Koh Samui Weather By Month
Live forecasts update automatically; written guidance last reviewed 23 June 2026 by the Aussie Report Weather Desk. Data from the Bureau of Meteorology (BOM) and other national met services via Open-Meteo.
Live data from Open-Meteo · updates automatically ·
Expect peak dryness from December to February, when monthly rainfall drops to 30–80 mm and daytime highs sit around 29–31°C. The live forecast above gives the current conditions, but for planning, March and April are the hottest months, while October and November see the heaviest rain.
What is the best month for sun and low rain?
January and February deliver the most reliable dry weather, with average rainfall of 30–50 mm per month and 8–9 hours of daily sunshine. Daytime temperatures range 29–31°C, and sea breezes keep humidity comfortable. This is the high season, so book accommodation early.
How does the monsoon affect monthly weather?
The northeast monsoon brings a wetter period from October to December. October averages 300 mm of rain, November is the wettest month with around 350 mm, and December still sees 150–200 mm. From March to May, the transition to the southwest monsoon brings rising heat — March and April top 33°C — before afternoon showers increase from June onward.
Is Koh Samui rainy in September?
September sits in the wet season, averaging 160–200 mm of rain. Showers are often short and heavy, followed by sun. Temperatures remain warm at 30–32°C, so it’s still viable for travel if you don’t mind some humidity.
What is the weather like in February?
February is one of the driest and most comfortable months. Expect daytime highs of 29–31°C, low humidity, and only 30–40 mm of rain. It’s ideal for beach days and outdoor activities with plenty of sunshine.
Can I get a 30-day forecast for Koh Samui?
A reliable 30-day outlook is not possible due to tropical variability. The live forecast above gives the most accurate 7–14 day view. For longer planning, use the monthly averages for rainfall and temperature ranges provided on this page.
Sources
For other destinations, check the Australia weather hub or compare conditions with Brisbane weather and Perth weather.