If you’re planning on visiting Thailand, you’re probably wondering when the best time of year is for your holiday. What is the weather and climate like in Thailand?

Well after living in Thailand for over 2.5 non-consecutive years in three different parts of the country (Bangkok, Koh Tao, and Chiang Mai), I’m here to shed some [sun]light on what Thailand’s seasons are really like, because the guidebooks don’t paint the full picture.

Here’s the truth about Thailand’s weather so you can plan your very best trip in Southeast Asia.

Thailand’s seasons  – the Mainland

As I’ve said, I’ve lived in Bangkok, Chiang Mai, and Koh Tao. Bangkok is located on the mainland in the middle of the country; Chiang Mai is located up in the mountains in the northeast of the country; and Koh Tao is an island in Thailand’s Gulf in the south of the country. All three have different seasonal patterns.

Thailand’s mainland experiences three main seasons, with each season more pronounced in Chiang Mai than Bangkok. This means in Chiang Mai, hot season is hotter, rainy season is rainier, and the cool winter season is even more gorgeous.

Here’s Thailand’s weather on the mainland broken down by season:

Hot season (March – May)

• Dry, sunny, very hot days.
• In Chiang Mai, this coincides with “smoky season”, meaning the farmers are burning their fields and smoke gets trapped in the city. The air is incredibly polluted and disgusting in Chiang Mai during this time.

Rainy season (June – September)

• In Chiang Mai, this truly means what it sounds like. Lots of grey skies and rain daily.
• In Bangkok, it’s usually dry during the day and the clouds gather for a downpour in the late afternoon, then it clears up.
• This season coincides with Thailand’s low season for travel. You can find lower prices around the country during this time as businesses experience a lull in tourism.
• Some people really like rainy season on the mainland because temps cool down and waterfalls are flowing. (I’m not fan personally. I’ll take hot and sunny over rainy and grey any day.)

“Winter” season (October – February) 

• This is the cool, dry season. I use the terms “winter” and “cool” loosely because it is not actually cold by any means, just cooler than at other times of year.
• Winter is especially gorgeous up north in Chiang Mai, with nights cool enough to necessitate a long sleeve shirt!
• Bangkok gets nice as well during this time.

Thailand’s seasons  – the Gulf

Here’s what I can tell you about the weather in the south of Thailand, based on my experience living on Koh Tao:

Hot season (February – May)

• Dry sunny, hot days, but it’s not nearly as hot as on the mainland because of the proximity to the ocean.
• The sea is clear and calm. (Great for scuba and also coincides with lots of whale shark sightings. This is the most beautiful and best time to visit the islands in my opinion.)

Shoulder season (June – October)

• Weather is unpredictable. Rainy/cloudy and sunny periods come and go. It’s really a toss-up what you’re gonna get.

Rainy season (November – January)

• Koh Tao experiences a monsoon season in December/January, while the rest of the country is in beautiful, cool, dry “winter”.

When is the best time to visit Thailand weather-wise?

It really depends where you want to go and what you want to see/do.

In my opinion, the best time would be during the hot season (February-May), because I would prioritize great beach days and lots of snorkeling/scuba on the islands. However, if you’re really into hiking and spending time in the mountains in the north and don’t care about rain during your beach time, you might prefer to come during the winter (October-February).

I don’t see a lot of compelling reasons to come during the rainy season as the weather sucks up north and isn’t great in Bangkok and is basically unpredictable in the south at this time. Unless you are really into the idea of avoiding crowds as much as possible, I wouldn’t come during this time.

I don’t recommend trying to rely on weather forecasts online. From what I can tell, weather forecasting in Thailand is never right. There are only three ways I’ve found of knowing what weather you can expect in a given place:

1. Check the Instagram stories for the hashtag of the place you’re heading to in the days preceding your trip (e.g. watch the stories for #kohtao to see what the weather is like there)
2. Look at the sky.
3. Ask a Thai fisherman or boat captain. I don’t know how they know, but they seem to always know.