May in Wengen is the rainiest month of the year. In May, the weather in Wengen is typically warm. Average daily high temperature in May is about 9 degrees above zero. On average, Wengen has 25 rainy, 4 sunny, and 2 partly cloudy days in May. The rains are usually heavy. May as well as March, April, June, and July is considered the most uncomfortable time to visit Wengen.