If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Kirn: The hottest months are usually July and August with an average temp of 56°F, while the coldest months are February and January with an average of 41°F. The rainiest months in Kirn are October, December, November, and January, with each month seeing an average of 7 inches of rainfall.