May in Isafjordur is the sunniest month of the year. In May, the weather in Isafjordur is typically cold. Average daily high temperature in May is about 4 degrees above zero. On average, Isafjordur has 22 rainy, 5 cloudy, and 4 sunny days in May. The rains are usually heavy. May as well as January, April, June, and July is considered the most uncomfortable time to visit Isafjordur.