Thailand doesn't have one weather. It has three regions that each keep their own calendar: the mountainous north, the Gulf of Thailand on the east side of the peninsula, and the Andaman Sea on the west. On most days of the year it's good somewhere. What matters is matching the month to the places you want to see.
This guide starts with the big picture, then goes month by month. For routes, costs and the rest of the planning, see our Thailand travel guide.
Thailand's seasons at a glance
Most of Thailand has three seasons:
- Cool and dry, November to February. The best weather: sunny, lower humidity, cool nights in the north.
- Hot, March to May. Temperatures climb to about 35°C in Bangkok and Chiang Mai in April. The north is smoky.
- Rainy, May or June to October. Usually heavy afternoon showers rather than all-day rain, with September the wettest month in Bangkok.
The Gulf islands don't follow this pattern. Their rain comes later, from October to December, and peaks in November, which makes them the best beach choice in the middle of the year.
| Month | Bangkok | North (Chiang Mai, Pai) | Gulf (Samui, Phangan, Tao) | Andaman (Phuket, Krabi, Phi Phi) |
|---|---|---|---|---|
| January | Dry, about 32°C | Cool and dry | Good | Best |
| February | Dry | Good, smoke from late Feb | Best | Best |
| March | Hot | Smoke, the worst month | Best | Good |
| April | Hottest, about 35°C | Smoke and heat | Best | Good, getting wetter |
| May | Rains begin | Rains begin, smoke clears | Good | Monsoon starts |
| June | Showers | Green, showers | Good | Monsoon |
| July | Showers | Green, showers | Good | Monsoon |
| August | Wet | Wettest month | Good | Monsoon |
| September | Wettest month | Heavy rain | Mixed | Wettest month |
| October | Drying out | Good, very green | Rains start | Wet, improving at month's end |
| November | Dry | Very good | Worst month | Drying out |
| December | Dry, about 31°C | Cool and dry | Improving | Best |
Climate averages from weather2travel.com. Every year is a little different, so treat these as a guide, not a promise.
Best time for each region
Bangkok
November to February is the most comfortable time, with daytime highs of about 31 to 33°C and almost no rain. March to May is hot and humid. The rainy season brings short, heavy downpours from May, and September is the wettest month, averaging about 290 mm. You can visit Bangkok in any month, but plan indoor options for the afternoons from June to October. Our Bangkok weather guide has more.
Chiang Mai, Pai and the north
The north is at its best from November to mid-February: dry, clear and cool, with Chiang Mai around 28°C by day in December and January and nights around 13 to 14°C. Pai, higher up, can drop to about 10°C at night.
From about late February to April, farmers burn fields and forests, and smoke fills the valleys. It's worst in March. In 2026, some districts, Pai included, were declared disaster zones because of the air, and in early April Chiang Mai ranked among the most polluted cities in the world. If you're sensitive to smoke, avoid the north from about February to April (March is the worst). The rainy season (May to October) turns everything green. It's a lovely time, though the Chiang Mai to Pai road gets slippery. See Chiang Mai weather by month.
Gulf islands: Koh Samui, Koh Phangan and Koh Tao
The Gulf is best from February to September. Its rainy season is October to December, and November is by far the worst, with about 460 mm of rain on Samui and rough seas that can cancel ferries for days. Ang Thong Marine Park closes from about 1 November to mid-December. If you want the beach between June and September, this is where to go. See the Koh Tao, Koh Phangan and Koh Samui guides.
Andaman coast: Phuket, Krabi, Phi Phi and Koh Lanta
The Andaman side is best from November to April, with the calmest, clearest sea from December to March. From May to October the southwest monsoon brings rough seas and a lot of rain (Phuket gets over 300 mm of rain in September). Some boats and island resorts close, and the Similan Islands national park shuts for the monsoon from mid-May to mid-October (it reopens on 15 October in 2026). Maya Bay on Koh Phi Phi Leh closes to landings for two months each year to let the reef recover. In 2026 that was 1 August to 30 September, and it reopened on 1 October. See the best time to visit Phuket.
Thailand month by month
Thailand in January
The best all-round month. It's dry and sunny almost everywhere, the north is cool, and both island coasts are calm, though Samui can still see some showers early in the month. It's also high season, so prices peak and popular places are busy. Book trains, flights and island stays early. The Full Moon Party on Koh Phangan falls on 22 January 2027.
Thailand in February
Nearly as good as January. The first three weeks are ideal for a trip that combines the north and the islands. From about 20 February the smoke starts building in the north, so do the mountains first and the beaches second. Chinese New Year falls on 6 February 2027, with celebrations in Bangkok's Chinatown and more domestic travel that week.
Thailand in March
A good beach month on both coasts, with hot, dry weather and calm seas. It's the worst month for smoke in the north, though, so this is a month for the islands and Bangkok. Diving in the Gulf is at its best from about now into April.
Thailand in April
The hottest month, with highs of about 35°C in Bangkok and Chiang Mai. The islands are still good, and the Gulf is at its calmest. The big event is Songkran, the Thai New Year water festival, from 13 to 15 April, when the whole country turns into a water fight. It's huge fun in Bangkok and Chiang Mai, but the north is still smoky and very hot. Read our Songkran guide before you go.
Thailand in May
The shoulder season starts. The rains begin in Bangkok and the north, which also clears the smoke. The Andaman coast gets rough from about mid-May, but the Gulf islands are still good. Prices drop and the crowds thin.
Thailand in June
A good-value month. It's the start of the green season in the north, with showers that usually come in the afternoon. The Gulf islands have some of their best weather while the Andaman coast is in its monsoon. For a north-plus-islands trip, June to August is the best time outside the peak season.
Thailand in July
Much like June, with a bit more rain and summer-holiday crowds from Europe. The Gulf islands are still good for diving and beaches. On the Andaman side, expect rough seas and some closed boat routes. It's a good month for Chiang Mai and Pai if you don't mind the odd downpour.
Thailand in August
The north is at its wettest (Chiang Mai averages about 225 mm), but mornings are often clear. The Gulf islands are a good choice and among the busiest places in the country. Maya Bay on Phi Phi is closed to landings in August and September. If you're choosing a beach in August, go to Samui, Phangan or Tao.
Thailand in September
The wettest month for most of Thailand. Bangkok averages about 290 mm and Phuket over 300 mm. Rain on the Gulf islands is mixed, and they're usually the best bet. Prices are at their lowest, and some travellers love the quiet, green countryside. If you're flexible about the weather, it's a bargain month. If you want guaranteed sun, go another time.
Thailand in October
A month of change. The rains ease in Bangkok and the north, which is lush and green by the end of the month. The Gulf islands start their wet season, and the Andaman side starts to dry out towards the end of the month. The Similan Islands reopen on 15 October, and Maya Bay on Phi Phi reopened on 1 October. Phuket's Vegetarian Festival runs from about 10 to 18 October 2026. The Full Moon Party moves to 27 October in 2026 because of the end of Buddhist Lent.
Thailand in November
A great month for the north and Bangkok: dry, fresh and green. Loy Krathong falls on 24 November 2026, when people float small candlelit rafts on rivers and lakes across the country, and Chiang Mai holds its Yi Peng lantern festival at the same time, with the main lantern nights on 24 and 25 November. The Full Moon Party on Koh Phangan falls on the same night as Loy Krathong. Lantern releases only happen at licensed venues outside the city on set nights. It's also the worst month for the Gulf islands, so if you want a beach in November, head to the Andaman coast, which is drying out. See our Loy Krathong and Yi Peng guides.
Thailand in December
Peak season starts. The whole country is dry by mid-month, except the Gulf islands, which improve through December. Ang Thong Marine Park reopens around mid-December. Christmas and New Year are the busiest and most expensive weeks of the year, so book well ahead. The Full Moon Party falls on 24 December in 2026, with an extra New Year's Eve party on 31 December.
Festivals and events by month
| Month | Event | Where |
|---|---|---|
| January | Full Moon Party (22 Jan 2027) | Koh Phangan |
| February | Chinese New Year (6 Feb 2027) | Bangkok's Chinatown and nationwide |
| April | Songkran (13 to 15 April) | Nationwide, biggest in Bangkok and Chiang Mai |
| October | Vegetarian Festival (about 10 to 18 Oct 2026) | Phuket |
| November | Loy Krathong (24 Nov 2026) and Yi Peng | Nationwide, and Chiang Mai |
| December | Full Moon Party (24 Dec 2026) and New Year's Eve | Koh Phangan |
The Full Moon Party runs every month. See the Full Moon Party guide for dates. Since 29 May 2026, alcohol can be sold from 11am to midnight with no 2pm to 5pm gap. Sales still stop nationwide on the main Buddhist holy days, and a few events move as a result.
When is the cheapest time to visit Thailand?
May to October, the rainy season, is the cheapest time for flights and rooms, with September usually the lowest of all. The Gulf islands are the exception to "rainy season", since June to August is one of their best periods, and they're busy with European summer-holiday travellers. The most expensive time is from mid-December to mid-January.
Best time for...
- A first trip covering Bangkok, the north and the islands: mid-December to about 20 February, or June to August with the Gulf islands.
- Beaches only: January to April on either coast, or June to September in the Gulf.
- Learning to dive: February to September on Koh Tao, or November to April on the Andaman side. The Koh Tao diving guide has more.
- Festivals: April for Songkran, November for Loy Krathong and Yi Peng.
- Avoiding crowds: May, June, September and October.
Plan your trip around the season
Our trips run in the months that suit their routes. Thailand in 2 Weeks and Thailand Express combine Bangkok, the north and the Gulf islands, so they run from mid-December to February and from June to August. The Islands Hopper crosses both coasts, so it only runs from January to April, when the Gulf and the Andaman side are both good.
