Best Time to Visit Thailand? It Depends on Which of Three Coasts

What is the best time to visit Thailand?

February, if you can only pick one month for the whole country. It is the one month when all three of Thailand's weather systems are dry together, and March comes close, except that it starts Chiang Mai's hot, smoky season. Every other month has at least one coast that is wet or turning wet.

Most guides give one window instead: November to February for the country, or November to March for the Andaman coast. That works for a two-week holiday. If you stay a month or more, the month and the coast matter much more, and the strip below shows why.

Read it by row. Phuket on the Andaman side is wet from May to November. Koh Samui in the Gulf is wet later, from October to December. Bangkok and Chiang Mai have one rainy season, from May to October. Only the ringed months are quiet on all four rows.

Planning December? See Thailand in December, coast by coast.

Where to be next: your month-by-month route, $19

A route for your months with a leave-by date for each stop, a backup, and the seasonal traps on your path. Drafted from 11 years of weather data, every number checked against it, in your inbox within 48 hours. Not included: visas, insurance or bookings.

See a sample plan Get my plan, $19

Why does Thailand have three different seasons?

The monsoon reaches the country from two sides. The west (Andaman) coast gets the southwest monsoon, from May to November. The Gulf islands sit behind the peninsula and get their heaviest rain from the northeast monsoon, from October to December. Bangkok, Hua Hin and Chiang Mai are inland of both and have a single rainy season.

So the two coasts are best at different times, and the Gulf is at its worst in the months guides tell people to go. The Wikipedia article on Koh Samui, which uses Thai Meteorological Department figures, also puts the heaviest rain there from mid-October to early December. Our numbers agree.

When is the rainy season in Thailand?

It depends on the coast. On the Andaman side (Phuket, Krabi, Koh Lanta) it runs from May to November, wettest in September. On the Gulf islands (Koh Samui, Koh Phangan) it runs from October to December, with November the peak by a wide margin, and January is still mixed. Bangkok and Chiang Mai are wet from May to October, heaviest in September and October in Bangkok and in August and September in Chiang Mai. For the winter months on four of the islands, see Koh Lanta against Phuket, Krabi and Koh Phangan, December to March.

When is the Andaman coast good?

February and March. Krabi has 38 and 59 mm in those months and Koh Lanta 23 and 43 mm, close to Phuket. Our where is warm in February page ranks Phuket and other places that are hot and dry that month.

The edges of the "November to March" window are weaker than the label says. In November Phuket still has rain on about 17 of 30 days, and Krabi on about 19. December cuts the rain by more than half, but about three quarters of the sky is still cloud. January has about the same rain as December on far fewer days (about 4 of 31 in Phuket), so it is mixed rather than dry. April turns back to rain on about 8 of 30 days in Phuket. If you read "dry season from November" and arrive in November, expect a wet month: see Phuket in November.

When are the Gulf islands good?

February to April; the best time to visit Koh Samui has the full picture. March is the driest month on the Gulf (47 mm on Koh Samui, 41 mm on Koh Phangan), and February's rain comes on few days, about 2 to 4 of 28. April is looser, but rain falls on about 5 of 30 days in Koh Samui against about 8 in Phuket. January is the in-between month: 152 mm on Koh Samui. Treat the Gulf as unsettled in January and good from February.

The Gulf's other good season is June to August, when the Andaman is at its wettest. Koh Samui gets 75 to 106 mm a month, against 295 to 401 mm in Phuket. It is not dry, but it is the best beach bet in Thailand during the European summer. Our Koh Samui point sits on the coast and reads a little cooler, and drier in summer, than the island's weather station.

When are Bangkok, Hua Hin and Chiang Mai good?

December to February. In December Bangkok has 9 mm, Hua Hin 19 mm and Chiang Mai 16 mm; see Hua Hin weather by month for the whole year. Chiang Mai is the cool one: a 27° high and a 16° low in January, against 31° and 22° in Bangkok.

After February the north heats up and fills with smoke. Chiang Mai reaches 34° in March and 35° in April, the burning season, so for clean air December to February is the window; the Chiang Mai burning season guide has the numbers. Its rainy season runs from May to October, with heavy storms in May and the most rain in August and September.

What should a remote worker do?

Our take, on weather alone. One month and free to choose: February, and any base works. December and January, with a beach: Hua Hin is the dry one (19 mm in December, against 80 mm in Phuket), because the Andaman is mixed until February. October and November: the Andaman and the Gulf are both wet, and Chiang Mai (61 mm in November) and Bangkok (77 mm) are the usable bases.

A good circuit for a winter: Chiang Mai or Bangkok for December, the Andaman for February, the Gulf for March and April. It follows the dry weather around the country instead of fighting it. The cards give each base in its best months.

Which base for which months?

• Phuket

  23 mm in Feb2 rain days in Feb

  Wet from May to November, 213 mm even in November.

  Suits: a beach base from February to March

• Koh Samui

  47 mm in Mar2 rain days in Mar

  The Gulf's wet months are October to December, with 457 mm in November.

  Suits: a beach base from February to April, and the one to pick from June to August

• Bangkok

  9 mm in Dec31° high in Dec

  Dry from December to February, wettest in September and October.

  Suits: city life and dry working weeks in winter; Hua Hin is the beach next door

• Chiang Mai

  8 mm in Jan16° low in Jan

  Cool mornings in winter, hot and smoky from March.

  Suits: december to February, before the burning season