Is It Monsoon in Thailand? Rainfall and Weather by City and Month

🇹🇭 Thailand 9 CITIES
Plan around the monsoon

Is it monsoon in Thailand?

Thailand's monsoon calendar splits by coastline more than it follows one national pattern. The Andaman coast, home to Phuket, Krabi, and the Phi Phi Islands, follows the classic southwest monsoon: wettest from around May through October, driest and sunniest from December through March. Bangkok and the inland north around Chiang Mai largely share that same May-to-October wet season. Further down the Gulf coast, though, Ko Samui and Songkhla see their heaviest rain arrive later instead, historically October through December, driven by a northeast monsoon that barely touches the Andaman side.

That split means there's rarely a single month when the whole country is simultaneously at its best. December through February comes closest to a nationwide sweet spot, dry and comfortable almost everywhere, but the shoulder months reward checking each specific coast rather than assuming one calendar applies from Chiang Mai to Ko Samui.

Regions at a glance
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Andaman Coast
Phuket, Krabi, and the Phi Phi Islands sit on Thailand's west-facing coast and follow the most classic monsoon pattern in the country: a long dry season from December through March, then a build-up of rain from May that historically peaks around September, with rougher seas and a real chance of delayed boat trips to the outer islands.
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Gulf Coast & the South
The Gulf coast doesn't move in lockstep. Ko Samui and Songkhla, further south, see their heaviest rain arrive later than the rest of the country, historically October through December, while Pattaya and Ko Chang, closer to Bangkok, follow a wet season closer to the mainland's own May-to-October pattern. Worth checking each city individually rather than assuming a single Gulf-coast calendar.
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Bangkok & the North
Bangkok and Chiang Mai both follow the mainland's southwest monsoon, wet from roughly May through October and driest from November through February. Chiang Mai's inland, hillier setting also brings seasonal haze from agricultural burning in the early dry season, a separate issue from the rains.
Ko Chang
Chiang Mai
Phi Phi Islands
Bangkok
Phuket
Krabi
Pattaya
Songkhla
Ko Samui
Frequently asked questions
Does all of Thailand have the same monsoon season?›
No. The Andaman coast (Phuket, Krabi, the Phi Phi Islands) and most of the mainland follow the southwest monsoon, wettest roughly May through October. Further down the Gulf coast, Ko Samui and Songkhla see their heaviest rain later instead, historically October through December.
What is the best time to visit Thailand overall?›
December through February is historically the closest thing to a country-wide dry season, comfortable and relatively low-rain in Bangkok, Chiang Mai, and along the Andaman coast alike. Ko Samui and the deep south can still see occasional heavy rain into early December.
Which part of Thailand is driest?›
Bangkok, Chiang Mai, and the Andaman coast all share a pronounced dry season from around December through March. The Gulf coast further south stays more changeable year-round.
Can I avoid the rain in Thailand by picking the right coast?›
To some extent. When the Andaman coast is deep in its wet season around September, the Gulf coast further south is sometimes only starting to see its own heaviest rain arrive, so timing and destination both matter, not just the calendar month.
Is Bangkok affected by the same monsoon as the islands?›
Bangkok generally follows the same broad southwest monsoon pattern as Phuket and Chiang Mai, wettest from around May through October, though as an inland city it doesn't see the same swell and boat disruptions the islands do.
Does typhoon season affect Thailand?›
Thailand sits mostly outside the main typhoon tracks that hit Vietnam and the Philippines, though the Gulf coast and southern peninsula can occasionally catch the tail end of a weakening storm.