Weather and best time to visit

Samui sits in the Gulf of Thailand and runs on a different rhythm to Phuket and the Andaman coast. The driest, sunniest stretch is roughly January–April; March–May is the hottest. The island's main rainy season is the northeast monsoon, roughly late October to December, with November typically the wettest — heavy downpours, rougher seas, and possible ferry/tour disruption (this is the key counter-intuitive point: Samui's worst weather is when much of Thailand is at its best). September–October can also see rain. There is a shorter wetter spell around June. Temperatures stay warm year-round (high 20s to low 30s°C); rain often comes as intense bursts rather than all-day grey.