Thailand
The two coasts have opposite rainy seasons, so somewhere is always dry.
When to visit Thailand
Across Thailand as a whole, September is typically the calmest month and December the busiest. Crowds are not uniform, though — see how the regions differ below.
Thailand is usually described as having three seasons — cool and dry from November to February, hot from March to May, wet from May to October — and for the mainland that is broadly right. The cool season is the high season, with November to February bringing the largest foreign crowds, the highest room rates and the most reliable skies over Bangkok, Ayutthaya and the north.
What that summary hides is that the two coasts do not share a calendar. The Andaman side, facing the Indian Ocean, takes the southwest monsoon from May to October and is at its wettest in September. The Gulf side, sheltered from it, keeps decent weather through those months and then takes its own rain from October to December, peaking in November. It is entirely normal for one coast to be washed out while the other, three hours away by road, is in full sun.
The domestic layer matters more than most visitors expect. Songkran in mid-April genuinely stops the country — offices close, buses and trains sell out, and much of the population travels home — and the Buddhist holy days scattered through the year bring nationwide bans on alcohol sales. Chinese New Year and the Chinese and Malaysian school breaks also move large regional crowds into the islands, independently of the European season.
It is not the same everywhere
The Andaman coast around Phuket and Krabi is soaked from May to October while the Gulf coast around Koh Samui and Koh Phangan stays comparatively dry through the same months and takes its own monsoon in November and December, and the northern highlands around Chiang Mai run cooler and drier than either but suffer serious agricultural burning haze from late February to April.
Getting around
Thailand is long — about 1,600 km from Chiang Rai to the Malaysian border — but cheap domestic flights cover it in an hour or two, overnight trains and buses link Bangkok to Chiang Mai and the south, and island transfers depend on ferries whose schedules thin out in the monsoon.
Crowds month by month across Thailand
Averaged across the 1 destinations we cover — tap a month for the full picture.
Weather across Thailand
Averaged across our destinations. The spread column shows how far apart the warmest and coolest are.
Where we have data in Thailand
Each city has its own crowd calendar and twelve month pages.
Every month in Thailand
Country-level tips
- Songkran (13–15 April) is the one date to plan around: domestic transport books out a month ahead, many businesses close for the week, and the water-throwing is nationwide rather than confined to one city.
- Alcohol sales are banned nationally on the major Buddhist holy days — Makha Bucha, Visakha Bucha, Asalha Bucha and Khao Phansa — and on election days, which surprises visitors every year.
- Book the north for December and January and the islands for the coast that is in its dry window; trying to do both coasts in one trip during the shoulder months usually means one of them is wet.
- Domestic flights are the practical way to cover distance, but budget carriers charge separately for bags and the low-cost terminal at Don Mueang is a long transfer from Suvarnabhumi, so avoid tight same-day connections.
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Frequently asked questions
When is the best time to visit Thailand?
The best time to visit Thailand is around September, when crowds across the country sit near 44/100 and average highs are about 33°C.
What is the quietest month in Thailand?
September is the quietest month across the destinations we track in Thailand, averaging 44/100.
When is Thailand most crowded?
Thailand peaks in December, when domestic and international travel overlap.