In July, the weather in Sejdisfjordur is typically cold. Average daily high temperature in July is about 10 degrees above zero. On average, Sejdisfjordur has 22 rainy, 6 cloudy, 2 sunny, and 1 partly cloudy day in July. The rains are usually heavy. July as well as January, March, April, and May is considered the most uncomfortable time to visit Sejdisfjordur.