If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Grisslehamn: The hottest months are usually July and August with an average temp of 59°F, while the coldest months are February and January with an average of 32°F. The snowiest months in Grisslehamn are December, January, November, and February, with each month seeing an average of 20 inches of snowfall.