Planning for the weather is an important factor for making your trip to Rottau a success, especially when you’re splurging. The hottest months are usually July and August with an average temp of 62°F, while the coldest months are February and January with an average of 34°F. The snowiest months in Rottau are December, January, November, and February, with each month seeing an average of 5 inches of snowfall.