In May, the weather in Chiang Rai is typically hot. Average daily high temperature in May is about 30 degrees above zero. On average, Chiang Rai has 27 rainy, 2 sunny, 1 cloudy, and 1 partly cloudy day in May. The rains are usually heavy. May as well as June, July, August, and September is considered the most uncomfortable time to visit Chiang Rai.