Koh Samui in September

December through May delivers Samui's best weather – dry, sunny, and breezy. This is peak season, so expect crowds and higher prices. Hotel rates jump 50-100% during European winter months. But here's Samui's secret advantage: it sits on the opposite monsoon pattern from Phuket and Krabi. While the west coast gets hammered by rain from May to October, Samui stays relatively dry. You might catch afternoon showers, but they pass quickly. Avoid October and November – this is genuine monsoon season with heavy, persistent rain and rough seas. Many restaurants and tour operators close during these months. Ferry services to other islands become unreliable. January and February offer the sweet spot: perfect weather, manageable crowds, and reasonable prices. March starts getting hot – temperatures hit 35°C regularly. April brings the hottest weather of the year, though sea breezes provide some relief. Book accommodations early for Chinese New Year and Songkran (April) – these holidays pack the island with domestic tourists.