The weather of Northern Thailand, including Chiang Mai, differs from the traditional divisions of spring, summer, autumn and winter. Instead, the region has three distinct seasons: the cool season, hot season and rainy season. Chiang Mai is known as the ‘cool capital’, and in comparison to the sweaty heat of Bangkok, the climate is far more agreeable.

Cool season in Chiang Mai

The most popular time for visiting Chiang Mai ( weather wise) is the cool season, which runs from December to the end of February. It is in fact pleasantly chilly in the evenings, and if you are planning on visiting Chiang Mai at this time of year, it would be wise to bring all-weather gear along; particularly if you intend hiring a motorcycle to get around, or going on a mountain trek. However, don’t leave out your summer clothes, as midday temperatures can climb well into the 30s (Celsius).

Hot season in Chiang Mai

Try to avoid a holiday to Thailand during this time (April-June) as unless you are completely accustomed to tropical heat, you will find the humidity utterly draining. Despite all the moisture in the air, however, there is virtually no rain during this period. The lack of water with blazing heat and slash-and-burn agricultural practices causes the usually lush green jungle that covers the surrounding hills to turn a charred brown from fires that burn almost constantly from January until the rains arrive. Not only does this affect the vegetation, but a trademark ‘hot season haze’ hangs over the entire city, obscuring the beautiful vistas.

The weather starts heating up in Chiang Mai around early February, and by mid-March, the nippy nights of December are nothing but a pleasant memory, with daytime maximums regularly reaching 40°C.

Rainy season in Chiang Mai

The southwest monsoon usually arrives from India at the end of May, and from then until November the weather in Chiang Mai and northern Thailand is very wet. The rainy season is characterized by torrential downpours, but they tend to be sudden bursts that only last for an hour or so rather than a steady stream of water.

Although mosquitoes are rife during this time, the rainy season is otherwise a pleasant time to visit the north. The rains bring respite from the heat, and the landscape returns to its strikingly-gorgeous shade of green. Rainfall is usually heaviest in September, with an average precipitation of 250mm.

Source：One stop Chiang Mai