The southern, coastal region of Thailand really has only two seasons – rainy season and dry season. Fortunately, for those planning a beach holiday, Thailand’s two coasts have slightly different rainy seasons, allowing visitors to find sunny beaches nearly year round. On the Andaman or west coast, where Phuket, Krabi, and the Phi Phi Islands lie, the southwest monsoon brings heavy storms from April to October, while on the Gulf of Thailand or east coast, where Koh Samui, Koh Phangan, and Koh Tao lie, the most rain falls between September and December.