Thailand weather: rainy season and when to go, destination by destination
Thailand does not have one rainy season but three weather patterns: the north and centre, the Andaman coast (Phuket, Krabi) and the Gulf of Thailand (Koh Samui). Here is the climate of each destination, month by month, from the official averages of the Thai Meteorological Department.
By Kylian Dev- 21 destinations
- Official 1991–2020 averages
- Rain and temperatures by month
In short
Overall, the best time to visit Thailand is November to April. The Andaman coast (Phuket, Krabi, Koh Lanta) is best from December to March. The Gulf islands (Koh Samui, Koh Phangan, Koh Tao) are the exception: they stay fairly dry from January to September but get their heaviest rain from October to December.
Weather
Thailand’s rainy season: three climates, so a different best time for each coast
North and centre
Bangkok, Chiang Mai, Pai, Kanchanaburi. Dry and pleasant from November to February, very hot in April, rainy from May to October.
Andaman coast
Phuket, Krabi, Khao Lak, Koh Lanta, Koh Lipe. Dry and calm sea from December to March; southwest monsoon from May to October.
Gulf of Thailand
Koh Samui, Koh Phangan, Koh Tao. Fairly dry from January to September, with the heaviest rain from October to December.
Weather
Thailand’s weather at a glance: seasons, coasts and months to avoid
The three seasons
Across most of Thailand the year splits into a cool dry season (about November to February), a hot season (March to May) and a rainy season (June to October). Bangkok’s official averages show the pattern: daytime highs of 32.7 °C in January against 35.7 °C in April, and rain of 24 mm in January against 336 mm in September. Chiang Mai’s cool season is cooler still, with average lows of 15.7 °C in January, while April is its hottest month, with highs of 36.7 °C. On the Andaman coast temperatures barely move: Phuket’s monthly highs stay between 31.8 and 34.4 °C all year, and what changes is the rain.
Gulf and Andaman do not follow the same calendar
The two coasts are almost mirror images. Phuket, on the Andaman side, gets 24 mm of rain in February and 350 mm in September. Koh Samui, in the Gulf, gets 64 mm in February but only 118 mm in September, then 445 mm in November, when Phuket gets 178 mm. That is why a trip built around the sea changes coast with the season: the Andaman coast from December to March, the Gulf islands for the middle of the year, from about June to September. Koh Tao and Koh Phangan are closest to the Koh Samui figures, and the Koh Samui station is the nearest official one for both.
Heat before the rain
March to May is the hottest stretch inland. Bangkok’s average high peaks at 35.7 °C in April and Chiang Mai’s at 36.7 °C, while the islands are gentler: Koh Samui’s highest monthly average is 32.9 °C, in May. If heat bothers you, plan the north and Bangkok for the cool months and keep the hot months for the coast.
Months to avoid, region by region
The official averages point to the wettest months of each region: September and October on the Andaman coast (Phuket 350 and 336 mm), October to December in the Gulf (Koh Samui 295, 445 and 263 mm), September and October in Bangkok and the centre (336 and 289 mm) and August in Chiang Mai (223 mm). These figures say when it rains most, not whether a trip is possible; the page of each destination gives rain and rain days month by month. For how the two monsoons work, plus ferries and diving, read our rainy season guide.
Go further
Open the weather page of your destination: Bangkok, Chiang Mai, Phuket, Koh Samui or Krabi and Railay. To choose a month, see when to go, or open a month page such as Thailand in November or Thailand in January.
Month by month
Rain month by month in each destination
Green means dry, amber some rain, blue rainy. Click a destination for the full climate table.
| Destination | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Best time |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Bangkok | November to April | ||||||||||||
| Chiang Mai | November to April | ||||||||||||
| Chiang Rai | November to April | ||||||||||||
| Pai | November to April | ||||||||||||
| Kanchanaburi | November to April | ||||||||||||
| Pattaya | November to April | ||||||||||||
| Hua Hin | November to August | ||||||||||||
| Koh Samet | November to April | ||||||||||||
| Phuket | December to March | ||||||||||||
| Khao Lak | December to March | ||||||||||||
| Khao Sok | December to March | ||||||||||||
| Koh Yao Noi | December to March | ||||||||||||
| Krabi | December to March | ||||||||||||
| Koh Phi Phi | December to March | ||||||||||||
| Koh Lanta | December to March | ||||||||||||
| Koh Samui | January to September | ||||||||||||
| Koh Phangan | January to September | ||||||||||||
| Koh Tao | January to September | ||||||||||||
| Koh Lipe | December to March | ||||||||||||
| Koh Chang | November to February | ||||||||||||
| Koh Kood | November to February |
Dry (under 100 mm)Some rain (100 to 200 mm)Rainy (over 200 mm)