With its geography ranging from rugged mountains in the north to low-lying islands in the south, the best time to visit Thailand depends on which region you are heading to. It features a warm tropical climate and generally high humidity throughout the year, with temperatures ranging from around 30°C/84ºF in December up to 36°C/97°F from January through to April.
Much of the country experiences heavy rains between May and October which make travel less favorable, however differing monsoon influences mean that the Gulf of Thailand islands can be bathed in sunshine at this time. With that in mind, Thailand is a year-round destination, provided you plan your trip by taking into account local climatic considerations.
Rainy Season (mid-May to October)
The southwest monsoon brings heavy rains across much of the country between mid-May and October, gathering moisture from the Andaman Sea and dumping heavy loads on the islands across the region. Seas tend to be choppy and you’re not going to get those postcard-perfect island vistas as seen in the travel brochures.
Bangkok is still bearable during late-May and June and you’ll benefit from reduced crowds at the major tourist sights. But the humidity builds up throughout July and August, with the combined heat and rain making September one of the most unpleasant times to visit.
The wet season doesn’t mean intensive rain throughout the day, but rather short rains for a few hours in the afternoon or evening. Things tend to be drier on the Gulf of Thailand side, as the northeast monsoon doesn’t hit the islands of Ko Phangan, Ko Samui, Ko Tao and Ko Chang until around October. Visitors flock to these islands during the North American and European summer holiday months of July and August, so book ahead if you plan on visiting during this period.
September and October tend to be the wettest months and many unpaved roads can become difficult to pass in the mountainous north, with trekking trails getting very muddy and slippery. But for great accommodation discounts and to experience Thailand away from the crowds (if you don’t mind getting wet), the rainy season shouldn’t be ruled out altogether as a time to visit.
If you want to experience the Rocket Festivals of Isaan, then mid-late May is the time to visit when homemade rockets are launched into the skies to herald the rains in villages across the northeast of the country. Or head to Chonburi in October for the annual Buffalo Racing Festival which features traditional food, music, beauty pageants and, of course, buffalo racing as part of this long-established rural celebration. October also marks the nine-day Vegetarian Festival which takes place in Phuket, honoring the Chinese belief that abstinence from meat during the ninth lunar month brings good health and happiness.
Cool Season (November to February)
As the rains ease in late October, temperatures also drop, heralding in the start of the cool season. This is one of the best times to visit Thailand, with lower humidity and heat in Bangkok for sightseeing and relatively dry skies across the Andaman Islands of Phuket, Krabi, Koh Lanta, Koh Phi Phi.
The weather contrasts on the east coast, however, and this is the rainy season in the Gulf of Thailand. It doesn’t usually experience the same intensity of rain as the Andaman coast does during its monsoon season, but expect some rainy days and less idyllic seas.
The mountainous north can get very chilly at night and during the early morning hours during the cool season, so warm clothing is essential. But the waterfalls are in full force following the rains and flowers are in bloom, making this a great time for trekking to the hill tribe villages.
The cool season is also the busiest in Thailand, so if you plan on traveling during this period you may need to book accommodation and transport in advance. If you want to beat the crowds, then visit during early November before the Australian summer holidays kick in and accommodation prices inflate over the Christmas/New Year break.
November marks the annual Loi Krathong or “Festival of Light” which draws thousands of visitors to Chiang Mai to witness floating lanterns being released into the night sky and along its waterways. But the first weekend in February is also a great time to visit this northern hub when the Chiang Mai Flower Festival is held, featuring colorful displays of chrysanthemums, as well as the unique Damask Rose. Chinese New Year is also held in February and is celebrated with particular fervor in Bangkok where the streets ignite with dragon parades and firecrackers.
Hot Season (March to mid-May)
Temperatures begin to rise from March into the mid 30°Cs/80ºFs and combined with the humidity can make things unbearable in Bangkok, particularly in the month of April. The northern uplands also see high temperatures and humidity levels, with the northeast experiencing the worst conditions as heavy clouds of dust blow over the dry fields.
This is a good time to escape to the islands and beach resorts of the Andaman Sea which are generally bathed in sunshine, with a range of water sports providing a welcome respite from the heat. The start of May often sees a drop in prices at many resorts with the coming rains, providing a great opportunity to grab a deal while the weather is still favorable.
The hot season coincides with the “Water Festival” of Songkran which heralds in the traditional New Year each April and sees an influx of tourists to the country. Thais take to the streets to soak one another with water pistols, balloons and buckets full of water, bringing welcome relief from the stifling heat. The “Ghost Festival” of Phi Ka Thon is also held during this period in the town of Dan Sai, with masked devotees parading through the streets, Buddhist monk sermons and rocket festivities as residents seek protection from the Mun River spirit, Phra U-pakut.