Best Time to Visit Thailand

The cool season runs from November to February. "Cool" is relative, since Bangkok still averages highs of 32–34°C, but humidity drops, rain almost stops (Bangkok sees 1–4 rain days a month) and the north gets genuinely fresh nights, around 16°C in Chiang Mai in January. It's the best season for everything, which is why it's also the most expensive. December is the busiest month of the year, and Christmas to New Year on the islands needs booking months ahead.

The hot season runs from March to May. April is the peak, with average highs of 35.7°C in Bangkok, 36.7°C in Chiang Mai and 36.2°C in Isan, and humidity makes it feel hotter. The beaches are still good (March is dry on both coasts), and April brings Songkran, the national water fight on 13–15 April. The drawback is the north, where crop-fire smoke from mid-February into April makes the air some of the worst in Asia.

The rainy season runs from May to October. Rain usually arrives as a heavy storm in the afternoon or evening, and mornings are often clear, so the season is wetter than it is gloomy. Prices and crowds fall, the countryside turns green, and the Gulf islands are in their good months. The problems are the Andaman sea, where boats get canceled and Maya Bay closes from 1 August to 30 September, and September itself, the wettest month in Bangkok, Phuket and Isan.

The Andaman coast (Phuket, Krabi, Railay, Koh Phi Phi, Koh Lanta, Koh Lipe and Khao Lak) is best from December to March, good in November and April, and at its worst from June to October, when the southwest monsoon brings 16–19 rain days a month and rough water. Phuket's two wettest months are September (350 mm) and October (336 mm), so October isn't a shoulder month on this coast. For the full picture, see the best time to visit Phuket.

The Gulf islands (Koh Samui, Koh Phangan and Koh Tao) work the other way. Their driest stretch is February to April, and June to September is decent, with 10–11 rain days a month but short showers rather than days of rain. Their rains come from October to December, peaking at 445 mm in November. If your trip is in July or August, this is where the beach goes. The best time to visit Koh Samui has the month-by-month detail.

The east coast closer to Bangkok splits in two. Pattaya and Hua Hin get relatively little rain until September and October, their wettest months, so they're reasonable mid-year escapes. Koh Chang is the exception that catches people out. It sits in the path of the southwest monsoon and gets over 1,000 mm of rain in July, so go in its dry season, November to March.

Bangkok is a year-round city, but November to February is when walking between temples is pleasant rather than punishing. In the rainy months a storm most afternoons is normal and rarely stops anything, and hotel rates drop. The months I'd plan around are April, the hottest, and September, the wettest at 336 mm over about 18 days. The best time to visit Bangkok breaks it down month by month.

Northern Thailand has the most to gain from good timing. November to January is the clear, cool season for trekking, Doi Inthanon and the hill towns, and it includes the Yi Peng lantern festival in November. From mid-February to April the smoke season makes Chiang Mai's air unhealthy, and that's the one window I'd tell anyone with asthma or young kids to avoid. The rains from May to September are lovely for green rice terraces and waterfalls, with August the wettest month. October is when the north clears first, so it's a good month to start a trip there. More in the best time to visit Chiang Mai.

The cheapest time to visit Thailand is the low season from May to September, with September, June and May the quietest months for arrivals. Flights to Bangkok are cheapest in those months, and hotels in the shoulder and low months often run 30–50% below their December and January rates. Food, transport and activities cost about the same all year, so the savings are almost entirely flights and rooms.

The way to use it is to pair a cheap month with the right region. In June to August the Gulf islands are in their good season while national prices are low, so Koh Samui, Koh Phangan or Koh Tao give you a proper beach trip at low-season rates. Late October and early November are the other sweet spot for the north and Bangkok, when the rains have mostly stopped but peak pricing hasn't started. For what a day actually costs, see the Thailand travel costs page.

The worst time to visit Thailand is September, the wettest month in Bangkok, Phuket and Isan. It's not a write-off, since rain mostly comes in afternoon storms and the Gulf islands are fine. But it's the month when Andaman boats are most often canceled and you'll lose the most hours to rain.

Two other windows are worth avoiding for specific trips. The north from mid-February to April is the smoke season, and Chiang Mai regularly has some of the world's worst air quality in March. The Gulf islands from October to December are wet, with November the peak. And Songkran week (13–15 April) is either the best or worst time depending on whether you came for it. Transport sells out and you will get soaked.

If you're combining the two, February to early April lines up best. Thailand is dry on both coasts (skip the north from March), and Vietnam is in its good season in all three regions. The north around Hanoi and Ha Long Bay is best from October to April, the center around Hoi An from February to August, and the south around Saigon from December to April. Avoid October and November, when typhoons can close Hoi An's beaches and the Gulf islands are wet. Thailand vs Vietnam compares the two in more detail.