May in Potsdam is the rainiest month of the year. In May, the weather in Potsdam is typically warm. Average daily high temperature in May is about 17 degrees above zero. On average, Potsdam has 18 rainy, 7 sunny, 5 partly cloudy, and 1 cloudy day in May. The rains are usually heavy. May as well as March, April, October, and November is considered the most uncomfortable time to visit Potsdam.