Introduction to
Thailand Weather and
Best Time to Travel

"Thailand Weather" was last updated on Feb 12, 2012 
All information below is subject to change

Thailand has a tropical and humid climate throughout the year!

But many backpackers prefer to travel during the cool season because they love the mix of sunny Thailand weather, and the refreshing cooler climate.

The year in Thailand can roughly be divided into three seasons: cool season (Nov-February), hot season (March-May) and wet season (June-Oct).

In general:

Even it's called the wet season, it doesn't rain for a long period in Thailand. There's usually short rain showers followed by sunshine. And if you want cheap accommodation in Thailand, traveling during the wet season is the ideal time of year.

And the same applies for the cool/hot season!

Even if you're traveling during the cool/hot season, you have to expect some rain in most parts of the country. It's not guaranteed that it won't rain.

Note: The temperatures mentioned below are average monthly daytime temperatures.


Weather in Bangkok

Bangkok is like any city in Southeast Asia: hot and humid through out the year! The temperature can rise up to 36°. During the wet season it will usually rain in the afternoon, and some days it will rain all day.

  • Nov to Feb: Min 21°, Max 33° 
  • March to May: Min 24°, Max 36° 
  • May to Oct: Min 24°, Max 34° 
  • Heaviest rainfall: September and October

I've visited Bangkok in November, December, January, April and May. Evenings and nights in November were cooler, while in December the temperature started rising as well as January. April and May were hot and humid day and night. 

Here's the weather forecast for Bangkok - updated by Thai meteorological Department.

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Weather in Chiang Mai and Pai

There's of course tropical climate in Chang Mai and Pai but it's cooler and less humid than other parts in Thailand. The temperature will drop at nights (even in the cool season in December and January), so you should definitely bring a sweater.

Most of my days in Chiang Mai and Pai in November were sunny during the day, and then it started to get chilly after sunset. 

  • Nov to Feb: Min 14°, Max 32°
  • March to May: Min 19°, Max 36°
  • May to Oct: Min 22°, Max 34°
  • Heaviest rainfall: August and September

Here's the weather forecast for Chiang Mai - updated by Thai meteorological Department.

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Eastern Coast (Gulf of Thailand)

Now we have reached Southern Thailand. Southern Thailand has only two seasons: wet and dry.

Weather in Koh Tao, Koh Pha Ngan, Koh Samui

Weather in Koh Tao, Thailand, in April

During the cool/hot season, the days on the islands are mostly sunny, but you'll occasionally feel the strong breeze/wind. The average temperature all-year is about 30°!

The period between September to November is known as the wet season. You'll experience rain showers once in a while, but only for a couple of hours.

We stayed on Koh Pha Ngan mid-December for 10 days. 6 of 10 days were overcast followed by sunshine, but it was still hot during daytime. You'll notice that the weather here is pretty much unpredictable (as rest of Thailand).

If you're considering traveling in Koh Tao, Phangan and Samui during April and May (the hottest months), I can tell you that it's VERY hot! I'm guessing between 30-35°.

We traveled in Koh Tao and Phangan at the end of April and beginning of May (2010), and the sun was scorching. I actually burnt my back when snorkeling, and I don't easily burn. Even when we were just walking, I would dehydrate after half an hour even though I drank one small bottle of water before we went out.

Spending your time on the islands during the hot months is something that I would recommend, due to the close proximity to the ocean.

  • Dec to Feb: Min 24°, Max 29°
  • March to August: Min 25°, Max 33-35°
  • September to Nov: Min 24°, Max 31°
  • Heaviest rainfall: Sep/Oct - Dec

Best time to snorkel/dive (as in best visibility):

March - October

During this period there are few currents and the visibility can be 20 meters! March, April and May are considered as the best months for diving because of the combination of water clarity and guaranteed sunshine!

Average water temperature: 30°

Here's the weather forecast for Koh Samui - updated by Thai meteorological Department.

Ko Chang Island Weather

Sunny weather in Ko Chang island in January

After the monsoon months, you'll likely experience cooler nights in November and December on Ko Chang Island. March to April are the hottest months. If you're planning on staying a lot in the water, you can probably handle these months.

From May to October it rains a lot. But don't get me wrong... it doesn't rain constantly. There has actually been sunny days during the wet season.

  • Nov to April: Min 20°, Max 35°
  • Mid-May to Oct: Min 24°, Max 32°
  • Heaviest rainfall: August

Best time to dive (as in best visibility):

Oct/Nov - May

The water visibility is variable and depends on where on the island you're heading. But the water clarity can reach 25-30 meters!

Average water temperature: 28° - 30°

Weather forecast for Trat (Koh Chang is located outside Trat) - updated by the Thai Meteorological Department.

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Western Coast (Andaman Sea)

Weather in Krabi, Ko Phi Phi island

From December to April you'll likely experience sun and blue skies. But there can be rain in the earlier months of the cool/dry season (Nov/Dec) because of the transition from the wet season. Otherwise the Thailand weather from Nov to Jan is mostly clear blue skies, some breeze and cool nights.

And if you can handle the hot and dry climate, the hottest months are March and April where the temperature range from 30-36°.

When I was in Ko Phi Phi in late December, 6 of 7 days were sunny. Some days started with overcast sky, then the scorching sun appeared around noon. The 7th day was overcast and there was a short rain shower in the afternoon.

  • Nov to April: Min 20°, Max 36°
  • May to Oct: Min 18°, Max 30°
  • Heaviest rainfall: October

Even if the period between May to October is called the wet season, there's more sun than rain.

Usually the rain will come in the evening. And during daytime there's a change of sun and cloudy skies. But it's still very hot during October, and the rainfall can cool you down.

Best time to snorkel/dive (as in best visibility):

February - May

The water is at its warmest and clearest during this time. Water visibility depends on which island you're going to. Average water clarity is between 
5-20 meters.

Average water temperature: 25-30°

I can tell you that when we snorkeled by Maya Beach in Mid-December, the currents were still strong but managable.

Here's the weather forecast for Krabi - updated by the Thai Meteorological Department.

Note: Notice that the two monsoons are affecting the west and east coast of Thailand differently.

Picture it this way: If it's less rain on the Eastern coast, it rains more on the Western coast! Ying and Yang!

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So, what conclusions
can we draw from this?

Thong Nai Pan beach in Koh Pha Ngan, Thailand
  • If traveling during the cool season, the weather is "perfect": a combination of sunny days + cooler nights. The downside is that you will encounter thousands of tourists during this period. It is the most popular time to travel to Thailand.
  • If you're a sun-lover and can handle the hot Thailand weather, head for Thailand during the hot season. And you'll likely share the beach with fewer people. 

Best of all, you will get a great snorkeling/diving experience because of the good water clarity and calm seas.But remember to drink lots of water. 

You are losing water even if you're not noticing it!The downside is that the Thailand weather during this time is HOT HOT! If you're staying a long time in Thailand, you might feel that you had enough of the sun!

  • If you're on a tight budget and want cheap accommodation, you should consider traveling during the wet season. 

The prices for accommodation are 30-50% cheaper than during the cool/hot season!But if you go diving, the water clarity is not at its best. And you have to accept the fact that it will rain.

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