July in Sejdisfjordur is the warmest month of the year. In July, the weather in Sejdisfjordur is typically warm. Average daily high temperature in July is about 12 degrees above zero. On average, Sejdisfjordur has 14 rainy, 9 cloudy, 5 partly cloudy, and 3 sunny days in July. The rains are usually moderate. July as well as April, May, June, and August is considered the most uncomfortable time to visit Sejdisfjordur.