In December, the weather in Isafjordur is typically cold. Average daily high temperature in December is about 1 degree above zero. On average, Isafjordur has 13 cloudy, 6 rainy, 6 partly cloudy, 5 snowy, and 1 sunny day in December. The rains are usually heavy. December as well as January, February, April, and May is considered the most uncomfortable time to visit Isafjordur.