May in Evanston is the rainiest month of the year. In May, the weather in Evanston is typically warm. Average daily high temperature in May is about 16 degrees above zero. On average, Evanston has 13 sunny, 12 rainy, and 6 partly cloudy days in May. The rains are usually moderate. May as well as February, March, April, and November is considered the most uncomfortable time to visit Evanston.