You can travel Thailand almost all year round, and that is exactly why “when should I go” is a harder question here than it looks. There is no month when it is bad everywhere, but there is no month when it is good everywhere either. That comes down to two things: the country has two coasts with opposite seasons, and the north has a stretch of the year you really want to avoid.
The big picture is simple. November to February is dry and pleasant, and that is the best time for a trip around the country. March to May is hot, with Bangkok feeling well over forty degrees. June to October is the rainy season, with the lowest prices and the greenest scenery.
But as soon as you add the islands, that story stops working. Below you see what each part of the year gives you, how the Andaman coast and the Gulf differ, and which places are at their best when.
The two coasts: the most important thing to know
Thailand has two coasts, and their seasons run the opposite way. On the Andaman coast, with Phuket, Krabi, Koh Lanta and Koh Phi Phi, it is dry from November to April. May to August is the rainy season, with showers but plenty of sunny days in between, and September and October are the wettest months, with rough seas and boat trips that get cancelled.
In the Gulf of Thailand, with Koh Samui, Koh Phangan and Koh Tao, it is the other way round. There, February to August is the best time, with a calm sea and visibility of up to thirty metres underwater on Koh Tao. October to December is monsoon with rough seas, and in November the ferries can sit still for days on end.
That means in November you can be having a perfect time on Phuket while no boat is running on Koh Tao, and in July it is the reverse. If you want both coasts in one trip, go when both are in season, from February to April, or accept that one of the two will be less than perfect.
Our verdict: pick your islands by your month, not your month by your islands
November to February: the best months for a trip around the country
This is high season, and for good reason. In Bangkok it is dry and slightly less sticky, with pleasant evenings and around thirty-one degrees during the day. In Chiang Mai it is dry and sunny and cool enough in the morning for a jumper, in Chiang Rai the nights drop towards ten degrees in December, and in Pai the mist fills the valley in the morning. On the Andaman coast the sea is calm and the water is clear.
The exception is the Gulf islands, where October to December is actually the wettest time. In January the weather turns there and the dry days start to add up.
Expect more travellers and higher prices in these months, and book your bed ahead on the popular islands.
Our verdict: come in these months if you only get one shot, and save the Gulf islands for the end of your trip
March to May: hot, and burning season in the north
These are the hottest months. In Bangkok it climbs to thirty-five degrees and feels well over forty, in Chiang Mai it reaches thirty-six and in Chiang Rai thirty-five. Plan your afternoons indoors and do your walking early.
There is one thing you really need to know about this stretch. In March and April it is burning season in the north: crop fires fill the air with smoke for weeks, the views over the mountains disappear and the air quality is bad. In Pai it is extra rough, because the village sits in a valley and the smoke stays there. If you want to do Chiang Mai, Chiang Rai or Pai, do not plan them for March or April. What burning season means for your plans is on our Chiang Mai page.
For the coasts, these months are actually good. On the Andaman side the dry season runs until the end of April, and in the Gulf the best season starts in February. April is also the month of Songkran, the water festival, and that turns a hot month into the most fun one of the year.
Our verdict: come in these months for the islands and Songkran, and save the north for another time of year
June to October: rainy season
The rain comes in short, heavy downpours, usually in the late afternoon, and in between it is simply dry. The scenery is at its greenest, the waterfalls are full and prices are at their lowest. In Chiang Mai and Chiang Rai the rainy season runs from May to October with showers in the afternoon, and green and clear the rest of the time, which makes it an underrated time to be there.
What you do need to know: on the Andaman coast, September and October are the wettest months. On Koh Lanta a lot of restaurants and hostels simply close, on Koh Phi Phi a lot of boats do not sail, and along the west coast of Phuket there is a strong undertow that costs lives every year. Watch for the red flags there and stay out of the water when they are up.
In Khao Sok, November is the wettest month of the year, with rain that settles in and a lot of tours that do not run. The best season there runs from December to April.
Our verdict: the rainy season works well for the north and the Gulf, and it is the cheapest time to travel
Place by place: when is each one at its best?
- Bangkok, Chiang Mai, Chiang Rai and Pai: November to February
- Khao Sok: December to April
- Krabi, Koh Lanta, Koh Phi Phi and Phuket: November to April
- Koh Samui, Koh Phangan and Koh Tao: February to August
Put those lists side by side and you see straight away which month fits which route. Coming in December? Do the north and the Andaman coast. Coming in July? Do the north and the Gulf.
How to plan a route around the weather
Start with your month and build your route around it, not the other way round. Coming in high season? Then the classic route from Bangkok through the north down to the Andaman coast is the obvious choice. Coming in summer? Flip it and finish on the Gulf islands.
In the autumn, always leave a day of slack before your flight home, because when the boats around Koh Tao are stuck it can last for days. How that route and those connections work is in our Thailand itinerary and in our guide to getting around Thailand.
Once you know when you are going, the next question is where exactly. Our Thailand page lines up all twelve stops, including the hostels and the daily budget for each one.
Can you visit Thailand in the rainy season?
Yes, and it is often the best time to be there. The rain comes in short bursts rather than all day, the scenery is at its greenest, prices are at their lowest and everywhere is a lot quieter. In the north and on the Gulf islands the rainy season is hardly a problem at all.
What you do need to watch is the Andaman coast in September and October. Those are the wettest months, the sea is rough, boat trips get cancelled and part of Koh Lanta shuts down. Want a beach in those months? Head to the Gulf.
And stay out of the north in March and April. Not because of rain, because there is none then, but because of the smoke from the burning season. That is the one time of year when we say: pick another month or another part of the country.
