Best beaches in Thailand

Andaman coast (Phuket, Krabi)

Typical swim months: December, January, February, March

Dry season roughly December to March. Southwest monsoon May to October brings heavy rain (Krabi October about 325 mm) and rougher seas with dangerous currents. April is hot with pre-monsoon showers; early November can still be very wet.

Rough sea and dangerous currents in the monsoon; west-facing beaches get higher waves June-September. Seasonal boat/tour reductions plausible but not documented in sources fetched.

Gulf of Thailand - Koh Samui

Typical swim months: January, February, March, April, May, June, July, August, September

Wettest months are October to December, November the peak at about 445 mm; the island is drier from mid-January to April and rains in May-September mostly as short showers. Sea is 28-30 C all year.

Heavy rain October-December; rain-days peak at 16 in Oct and Nov.

Eastern Gulf (Pattaya area)

Typical swim months: November, December, January, February, March, April

Dry season December to April; rainy May to mid-November with September-October heaviest. Source prefers December to mid-February before it gets hotter. Sea 27.5-30.5 C year-round. Pattaya is used as a proxy; islands like Koh Chang were not assessed.