Weather can make or break a roadtrip, so we've gathered some data about year-round temperatures in Rolla to help you plan yours. The hottest months are usually August and July with an average temp of 64°F, while the coldest months are February and January with an average of 13°F. The snowiest months in Rolla are April, March, October, and January, with each month seeing an average of 13 inches of snowfall.