May in Haiphong is the windiest month of the year. In May, the weather in Haiphong is typically hot. Average daily high temperature in May is about 29 degrees above zero. On average, Haiphong has 24 rainy, 4 sunny, 2 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 Haiphong.