If you’re hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Menomonee Falls: The hottest months are usually July and August, with an average temperature of 20°C, while the coldest months are January and February, with an average of -3°C. The snowiest months in Menomonee Falls are January, March, November and December, with each month seeing an average of 24 cm of snowfall.