If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Elmhurst: The hottest months are usually July and August with an average temp of 71°F, while the coldest months are January and February with an average of 30°F. The snowiest months in Elmhurst are January, March, November, and February, with each month seeing an average of 5 inches of snowfall.