Weather, seasons and regions

Mainland Thailand has three broad seasons: **cool/dry** (roughly Nov–Feb, the peak tourist season), **hot** (Mar–May, with April the scorcher), and **rainy/monsoon** (roughly Jun–Oct). But the **Gulf islands — Koh Samui, Phangan, Tao — run on a different clock**: their wettest stretch is typically October to December (often peaking around November), so Samui can be lovely when the Andaman coast (Phuket, Krabi) is rainy, and vice versa. Regions vary widely: cooler mountainous north (Chiang Mai), hot central plains and Bangkok, the Isaan northeast, and the tropical southern coasts and islands. Pack light, breathable clothing plus a light rain layer.