May in Warsaw is the rainiest and the cloudiest month of the year. In May, the weather in Warsaw is typically warm. Average daily high temperature in May is about 24 degrees above zero. On average, Warsaw has 13 rainy, 9 partly cloudy, 8 sunny, and 1 cloudy day in May. The rains are usually heavy. May as well as January, February, March, and June is considered the most uncomfortable time to visit Warsaw.