If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Les Belleville: The hottest months are usually July and August with an average temp of 54°F, while the coldest months are January and February with an average of 24°F. The rainiest months in Les Belleville are December, May, November, and January, with each month seeing an average of 7 inches of rainfall.