If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Monguelfo: The hottest months are usually July and August with an average temp of 54°F, while the coldest months are January and December with an average of 24°F. The rainiest months in Monguelfo are August, July, June, and May, with each month seeing an average of 11 inches of rainfall.