Weather

The Thais divide the year into three seasons: the cool season, hot season, and rainy season. For most westerners, this translates to "hot," "really hot," and "really hot and wet." Temperatures rarely drop below 25° C (70° F).

Chiang Mai is popularly known as the "cool capital." The reality is that in the hot summer months, Chiang Mai can be just as uncomfortably hot as much of the rest of the country. However, from December to February the nights can be cool enough to require a jacket, so the appellation is not totally undeserved.

The cool season runs from December to March, although there's usually just one week in December when temperatures are actually comfortable. The heat starts to increase soon after the new year and by April or May it can be almost unbearably hot and humid. During the rainy season the downpours can be extremely heavy, but generally only last for an hour or so in the afternoon.
 

The rainy season, which coincides with the European and North American summers, is not an entirely bad time to visit, since the rain generally falls within the span of an hour or two in the late afternoons. The rain cools down the temperatures a bit and cleans the air quite nicely. With the high temperatures, the rain is not exactly cold. Sometimes it can be like a warm shower.