If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Oppegard: The hottest months are usually July and August with an average temp of 59°F, while the coldest months are January and February with an average of 28°F. The snowiest months in Oppegard are January, December, February, and October, with each month seeing an average of 17 inches of snowfall.