Overview
Thailand's Andaman coast has two distinct seasons driven by the monsoons. The dry northeast monsoon (November–April) is the only practical window for sailing, bringing settled weather, light winds, and calm seas. The southwest monsoon (May–October) brings heavy rain, strong winds, and rough water that closes most charter operations.
Peak season: December–February
The peak runs December through February — bone-dry, sunny, and warm, with gentle 10–15 knot breezes and flat seas. This is the most reliable weather of the year. It's also the busiest and priciest, so book several months ahead.
Shoulder months: November & April
November marks the end of the wet season — greener landscapes, fewer crowds, and good value, with the occasional late shower. April is hot and humid as the dry season ends, but still sailable, with the best prices before the monsoon closes the season.
What to avoid
Avoid May through October. The southwest monsoon brings sustained strong winds, heavy rain, and big swells on the Andaman coast. Most charter companies don't operate, and conditions are unsuitable for relaxed cruising.