Thailand is a Southeast Asian country recognized as a destination for tropical beaches, grand palaces, ancient ruins, and Buddhist temples. Thailand has a tropical climate with a distinct monsoon season, which means that whatever time of year you visit, it’s going to be warm, humid, and might even be wet. There are three seasons in Thailand which can be described as the following: a cool season between November and February, a hot season between March and May, and a rainy (monsoon) season between June and October.
Heat, humidity, and rainfall vary significantly, depending on where and when you’re traveling.
Chiang Mai and the rest of the northern region of Thailand enjoys cooler, milder weather throughout the year. During the cool season, average highs are in the low 80s (Fahrenheit) and average lows dip down into the 60s. Temperatures can go even lower up in the mountains, making it the only region in Thailand where you’ll ever need a sweater outside.
Travelers should keep in mind that hot season temperatures can easily hit the mid-90s or higher during the day. The weather doesn't cool off much at night, although higher elevations in some areas make it more bearable than in the rest of the country. In regards to inclement weather, the rainy season sees less rain here than in other parts of the country. Regardless, monsoon storms can still be dramatic and intense, especially during September, which is the rainiest month of the year.
The best recommended time to visit Northern Thailand is between October and April, although travelers should keep in mind that this is peak tourist season.
Bangkok and Central Thailand
Bangkok's three seasons all share one thing in common: heat. In fact, the coldest temperature ever recorded in Bangkok was 50 degrees, and that was back in 1951. Cool season temperatures are generally in the 70s and 80s, so it’s no surprise that it’s such a popular time to visit.
During the hot season, visitors can expect highs in the 80s and 90s, with some days in the 100s. If you’re visiting Bangkok during the hot season, make sure to plan activities around the weather, as the heat makes it difficult to walk outside for too long. For most of the rainy season, temperatures cool off by a few degrees, and storms only last an hour or two before passing.
Tourist season is the highest in November through March for cities like Bangkok. Since the weather cools dramatically during December through February, it is suggested to travel during these cooler months.
The weather in Southern Thailand follows a slightly different pattern than the rest of the country. There’s really no cool season, as temperatures only vary by about 10 degrees between the hottest and coldest months of the year. It's typically between 80 and 90 degrees on average in cities like Phuket and the Central Gulf Coast.
The rainy season happens at different times on the peninsula, whether on the east or west side. If you’re in the west, where Phuket and other Andaman Coast destinations are, the rainy season starts earlier in April and lasts through October. If you’re on the east side, where Koh Samui and the other Gulf Coast destinations are, most of the rainfall happens between October and January.
Tourists most commonly travel to southern Thailand between November and February when the weather is cooler and drier. To avoid hot weather and monsoon season, it's recommended to travel during the more popular months.