In May, the weather in Dien Bien Phu is typically hot. Average daily high temperature in May is about 28 degrees above zero. On average, Dien Bien Phu has 28 rainy, 2 sunny, and 1 partly cloudy day in May. The rains are usually heavy. May as well as April, June, July, and August is considered the most uncomfortable time to visit Dien Bien Phu.