If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Menomonee Falls: The hottest months are usually July and August with an average temp of 68°F, while the coldest months are January and February with an average of 27°F. The snowiest months in Menomonee Falls are January, March, November, and December, with each month seeing an average of 9 inches of snowfall.