Thailand in May
May marks the start of the rainy season on the Andaman (west) coast — Phuket and Krabi. The Gulf islands (Koh Samui) are still in a relatively reasonable season at this time.
Weather by Region
Phuket and Krabi: the monsoon begins, more cloud and rain, the sea can be rougher. Koh Samui and Koh Phangan: still a reasonable season — their real rain arrives only in autumn.
Crowds and Prices
Start of low season — hotel prices begin dropping significantly, fewer tourists.
Recommended Destinations for May
Who Should Visit
Anyone planning the Gulf islands (Koh Samui, Koh Phangan, Koh Tao) — still good. Anyone planning Phuket/Krabi with rigid sea plans should check the forecast closely.