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Live forecasts update automatically; written guidance last reviewed 20 June 2026 by the UK Bullet weather desk. Data from national met services via Open-Meteo.
Live data from Open-Meteo · updates automatically ·
Koh Samui weather is tropical and warm year-round, with average highs of 30 °C, but the monsoon brings heavy rain from October to December. The live forecast above shows current conditions for Koh Samui Airport.
What is the best time to visit Koh Samui?
The driest and sunniest period is from December to March, though December often has lingering rain. The northeast monsoon affects the island mainly between October and January.
- Peak dry season (January–March): low humidity, calm seas and daily sunshine – ideal for beach holidays.
- Transition months (April–September): hot with sporadic showers; May to July see brief afternoon downpours.
- Rainy season (October–December): heaviest rainfall in November; short-lived storms but still warm.
What is the typical weather pattern by month?
Koh Samui weather by month varies noticeably because the island sits in a rain shadow during the southwest monsoon. The wettest months are October, November and December, while January and February are noticeably drier.
- Koh Samui weather October: increasing rain, average 280 mm; still very warm at 30 °C.
- Koh Samui weather November: wettest month with >400 mm; overcast but temperatures stay warm.
- Koh Samui weather December: improving as the month progresses; more sun towards New Year.
- Koh Samui weather January: one of the driest and coolest months, around 26 °C average.
- For longer-range planning, koh samui weather forecast 30 days and koh samui weather 15 days outlooks can give general trends, but tropical spells can shift quickly.
When is the rainy season in Koh Samui?
Rainy season runs from October to December, with November typically seeing the most rainfall. Short, heavy downpours are common, but they often clear quickly, leaving warm humid conditions.
What is Koh Samui weather like in December?
Koh Samui weather in December starts wet but improves as the month goes on. By late December, the northeast monsoon weakens, bringing more sunshine and making it a popular Christmas and New Year destination.
Do I need a weather app for a 14-day stay?
A 14-day outlook can help you pack for tropical showers. Use koh samui weather 14 days forecasts for general trends, but always check the live feed above for daily updates before heading out.
Sources
For a complete picture of Britain’s weather, visit our UK Weather Hub or check the 10 Day Weather Forecast UK for comparisons.