In Thailand, the rainy season is dominated by the southwest monsoon and usually lasts from July to October. However, the name “rainy season” is slightly misleading. While it certainly does rain during this season, it’s likely to consist of a heavy but short downpour in the evenings.
Fortunately for beach-lovers, Thailand’s different coasts have slightly different rainy seasons, allowing visitors to find sunny beaches year round.
In the South, on the Andaman or the west coast, where Phuket, Phang-Nga (Khaolak, Mu Ko Similan), Krabi (Ko Phi Phi, Ko Lanta) lie, the southwest monsoon brings storms from April to October. On the Gulf of Thailand or the east coast, where Ko Samui, Ko Phangan, and Ko Tao lie, the most rain falls between September and December.