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Live forecasts update automatically; written guidance last reviewed 23 June 2026 by the Coast Current Weather Desk. Data from the Bureau of Meteorology (BOM) and other national met services via Open-Meteo.
Check the live forecast above before planning your day on Koh Samui, as the island’s tropical monsoon climate means conditions can shift quickly between sunny spells and brief downpours.
What is the typical weather pattern on Koh Samui?
Koh Samui has a tropical monsoon climate with consistently warm temperatures year-round, averaging 27–30°C. The island experiences two main seasons: a dry season from December to March, and a wetter period from October to November. Unlike much of Thailand, Koh Samui’s heaviest rain often falls in October and November, while December and January bring cooler, breezier conditions with lower humidity.
How does the weather vary by month?
For those checking koh samui weather by month, the driest and most popular months are December through March, with plenty of sunshine and lighter winds. April to September sees more humidity and scattered showers, though still plenty of beach weather. The koh samui weather forecast 7 days or koh samui weather 14 days will give you a reliable short-term picture, but longer-range outlooks (koh samui weather forecast 30 days) are less precise due to the tropical variability.
Is Koh Samui weather in December good for a holiday?
Yes, December is one of the best months. Expect warm days around 28°C, lower humidity, and mostly clear skies. It’s part of the dry season, though brief showers can occur. Pack a light jacket for cooler evenings.
How accurate is the koh samui weather forecast 7 days?
A 7-day forecast for Koh Samui is generally reliable for temperature and broad rain trends, but tropical showers can be localised. Check the live forecast above daily for updates, especially if planning boat trips or outdoor activities.
Does Koh Samui ever get severe weather warnings?
Yes, during the monsoon transition (October–November), the Thai Meteorological Department may issue warnings for heavy rain or rough seas. For Australian travellers, our severe weather warning page explains how to interpret such alerts.
For broader Australian conditions, visit our Australia weather hub or check Sydney Weather and Melbourne Weather.