If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Kopervik: The hottest months are usually August and July with an average temp of 57°F, while the coldest months are February and January with an average of 39°F. The rainiest months in Kopervik are October, December, September, and November, with each month seeing an average of 10 inches of rainfall.