If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Deckerville: The hottest months are usually July and August with an average temp of 66°F, while the coldest months are February and January with an average of 28°F. The snowiest months in Deckerville are January, March, February, and December, with each month seeing an average of 11 inches of snowfall.