May in Madison is the rainiest month of the year. In May, the weather in Madison is typically warm. Average daily high temperature in May is about 19 degrees above zero. On average, Madison has 17 rainy, 7 sunny, 4 partly cloudy, and 3 cloudy days in May. The rains are usually heavy. May as well as January, February, March, and December is considered the most uncomfortable time to visit Madison.