Even though Thailand has a fairly forgiving climate for tourists, seasoned travelers will be the first to tell you that's it's always best to check the weather before you travel.
This is because seasons vary in different parts of the country.
Most people know that Thailand is in South East Asia, but few realize how much variation that could mean for a traveler who's unfamiliar to the region.
Depending on the city you touch down in, you could be headed into a tropical steam bath or a powdery dust bowl.
But no worries, this guide will help you book your trip around the varying weather conditions.
Thailand Weather: Region by Region
Thailand, as a whole, has three major seasonal differences to consider: hot & dry, hot & wet, and a cool season.
Although these seasons are true country-wide, the times for them in different areas can vary.
Also worth considering is how far south you are heading. The further south you go, the closer to the equator you will get and, depending on the season, that can mean monsoons or long afternoon heat swells.
General Seasonal Changes
A general country guide is as follows:
- Dry Season: March-May
- Rainy Season: May-October
- Cool Season: November-February
Okay, so that's a general overview, but let's break this down further and have a closer look at the five major regions.
The heart of the country is mostly flatlands, with the lower boarder falling into the Gulf of Thailand.
Humidity remains pretty consistent year round, but you will find all three seasons represented here.
The difference is, the seasons are more evenly spaced apart than the other regions.
February to June is the hottest time. Sunscreen and a hat are a must!
The heat is followed by the rainy season from June to October, where 1,400 millimeters of rain spills across the landscape annually.
However, you’re not likely to see any long, rainy days until the later part of the season – so feel free to plan some trips.
The slightly cooler season runs from October to January. The later part of the cool season may even produce a few cold days here and there. So pack a sweater if you’re planning on visiting during this time.
The home of sticky rice and spicy foods, the northeast is a dry plateau with few hills. However, they have rivers to rival the rest of the country and the monsoons usually bring these rivers to their spilling point.
Here they'll get the same 1,400 millimeters yearly average rainfall as the central folks.
In the June to October wet weather season, the rain brings the region’s natural settings to life – everything is deep verdant green and the waterfalls begin to gush with intensity.
November to February is the cool season. Travelers usually enjoy this time of year because it almost never rains and yet it’s not as steamy as it will be in the hot season, which is from March until May.
If you intend a stay the hotter months, make sure you book a room with air conditioning because temperatures will get to a lofty 35°- 45°C. But if you can endure the heat, you’ll find many cultural festivals during this time of year.
This East's climate is mostly similar to central Thailand; however, when the hot season kicks off in March, it's going to be a brutal 40-45 degrees Celsius until around October.
The cooler months –November to February – are usually very pleasant for those tourists accustomed to the European bitter cold at this time of year.
As true for the rest of Thailand, there are only a few days at a time of what could be considered “cold weather” during these months.
By May, the weather will bring on the rainy season. It's not uncommon to have intense weather during this season, but it doesn't often get heavy until closer to the end of October. Up until then, the storms last around 30 minutes or so.
Up here is mountain country, where crisp rivers separate many of the peaks and the climate swings are a bit more diverse, which is great for all kinds of agriculture, as well as for various type of traveler.
You’ll want to trek up this way If you’d like to avoid the sticky heat of the southern areas, but make sure to choose the right time or you’ll find it to be just as hot as everywhere else.
To make things worse, the drier terrain allows for crop burning in the hotter seasons that can make your travels less pleasant.
March and April are the hottest times of the year, followed by rains spanning from May until September. That being said, the further north you go, the more uncommon it is to see much rain until later in the season.
Even at that, it may only rain for a half an hour a day. But don’t let the rain turn you off. It is the best time for river rafting and other water fun and frolics.
If your intention is a more tropical, beach style holiday, the southern region of Thailand is exactly what you're looking for.
Luckily, down South you only worry about two seasons: the wet season, with monsoon rain from April to October, and the dry season from November to May.
Compared to the rest of the country, South Thailand gets the most rain. The skies dump about 2,400 millimeters yearly. Monsoons begin around May, bringing on the start of the rainy season. The wet weather can be almost continuous until October.
If you're lucky enough to catch a break in the rain though, you're guaranteed to have a very hot, humid, and steamy day. November will begin the dry season and temperatures at night can even fall to a light chill.
A Tourist's Guide to the Weather of Thailand's Most Visited Cities
Probably the most visited city in Thailand, with tons of things to see and do, the weather in Bangkok is fairly predictable.
During the rainy season, you’ll want to carry an umbrella, but it's not guaranteed you'll need it.
Rain is sporadic and downpours don't usually last more than 30 minutes to an hour.
Don't quote me on that though!
Bangkok has seen some pretty severe flooding in the past, though downtown usually drains pretty fast.
The rainy season is from July to October, and the cool season between November and February.
Average temperatures are 26°C, with highs around 33°C. The lowest you'll encounter is 21°C at night.
December is the coolest month, which makes it the perfect time for the tourist season. Attractions during this season will be at capacity.
Bangkok is pretty warm all year round but, during this season, average temperatures hit 31°C.
As the season progresses it will often get up to 34/35°C and rarely drop below 25°C.
Bangkok's hot season is strong from March to June, but, if you don't mind the heat, you'll find some good hotel deals and shorter wait times.
Some consider this place to have near perfect weather – as far as Thailand goes, anyway.
It doesn't get too much rain and isn't too uncomfortably hot. The average high is around 31°C and the low is around 22°C.
As another of the most visited places in Thailand, the cool season is when you'll find the most tourists here.
The hot season starts in March and doesn't cool until around the end of May. The temperatures climb to 33°C and rarely dip below 27°C.
Pattaya is a beach town, so the ocean winds help to curb the heat, but the humidity doesn't often quit – which can produce some rain. This is welcomed by most, because a good soaking tends to cool things down for an hour or two.
When the rainy season finally does set in between June and October, the storms will pour. Like Bangkok, they usually don't last long.
If you can manage an occasional downpour, you'll find slightly cooler temperatures and less crowded beaches. And this being the low season, you'll find better hotel rates too (see the link below).
As the second most populated city in Thailand, Chiang Mai is known as the ‘cool weather capital’.
In comparison to the sweaty heat of Bangkok, the climate can be far more agreeable.
The most popular travel season starts in December and lasts through February.
If you expect to be there at this time, you may find it a bit chilly at night, or if you head up near the mountains in the day.
I've witnessed temperatures as low as 4°C!
Make no mistake though, this is still Thailand and the days can still get up into the 30°C range.
By early February the daily high can hit 40°C.
March through June will continue that heat, and though there’s always an element of humidity in the air, rains won’t start until the end of May.
If you are looking for a summer time trip, you may want to hold off until July. Due to slash-and-burn farming practices, a smoky haze may cover the usually awesome mountain views, and clog up your airways.
More on the crop burning season here.
The rainy season in Chiang Mai arrives at the end of May and lasts until November. In these months, the weather can get pretty wet but, as in other parts of Thailand, the storm head passes rather quickly.
While the beaches aren't as good as down south, Hua Hin is a great almost year-round holiday destination.
The cooler season spans November to February, where at night temperatures fall to around 24°C. However, the days warm up considerably, with highs in the low 30s.
The hot season lasts from March until June, with April marking the start of the hottest months. Average temperatures are consistently in the low 30s.
The rainy season is from July through October, but Hua Hin won’t see heavy downpours with any frequency.
Being right on the ocean’s coast keeps the air moving and cuts the humidity down too. The high will still be around 33°C in the day, and 25°C at night.
Another one of Thailand’s island provinces, this beautiful oasis is pretty much warm year-round, but can be prone to some wet weather.
April through May, and September through October, are the hottest times of year in Phuket – with an average temperature of 29°C, and a low of 23°C.
But that doesn't mean you won't see rain during these months.
May to October is monsoon season and you can expect to see between 18 and 23 days of rain a month.
September and October are usually the wettest months, but it's rare that the island will have more than two full rainy days in a row, and oftentimes rain falls through the night and it's dry by morning.
Though the temperatures don’t vary much, January has the coolest average temperature of the year, with highs around 32°C, and lows of 22°C.
The rains in Phuket begin a little earlier than in other areas. The majority of the rain falls at the beginning of the season – sometime around early May – with averages of up to 400mm a month.
Most travelers agree that November to February the preferred time to stay, as temperatures are just a bit cooler and rainfall is scarce.
Due to its proximity to Koh Phangan, Samui is famous as a stop-over for Full Moon party goers. This is Thailand’s third-largest island and one of the most-sought after destinations in Thailand.
Koh Samui is located fairly close to the equator, which keeps temperatures somewhat consistent throughout the year. The hot season comes between March and April and daily averages are often above 32°C.
The cold season starts in November and lasts through January. During this time high temperatures can still be 30°C, with the average low around 25°C.
The cool season is between December and February, when there is less rain. That makes this a popular time to visit this lovely island.
That said, the hot season from March until August does little to stop the tourists.
The beaches remain packed until the rain begins in September, which lasts until December.
With temperatures still at around the 30°C mark, it’s still warm in December and can be pretty sticky. The main difference is that the weather patterns are ever-changing with intermittent sunshine interrupting the rains.
Though the rains can get rather heavy, the downpours usually don’t last long. That said, flooding can occur and local residents are used to waist-high water in Chaweng after a serious downpour.
Take a chance in this low season for lower hotel prices and fewer crowds.
Wherever you’re headed in Thailand, you’re almost guaranteed to enjoy a holiday of a lifetime. I hope this guide has given you a good idea of where to go, when to go and what to pack.