May in Kempten is the rainiest month of the year. In May, the weather in Kempten is typically warm. Average daily high temperature in May is about 15 degrees above zero. On average, Kempten has 23 rainy, 7 sunny, and 1 partly cloudy day in May. The rains are usually heavy. May as well as January, February, March, and April is considered the most uncomfortable time to visit Kempten.