May in Rouen is the rainiest month of the year. In May, the weather in Rouen is typically warm. Average daily high temperature in May is about 16 degrees above zero. On average, Rouen has 19 rainy, 7 sunny, 4 partly cloudy, and 1 cloudy day in May. The rains are usually moderate. May as well as January, February, March, and November is considered the most uncomfortable time to visit Rouen.