Aren’t February and March usually the coldest months?
Intellicast's historic averages page lists the lowest temperature days in Dayton, Ohio as January 19-22. On average January is the coldest month followed by February and December.
January seems to be the coldest month here in se Wisconsin. February is cold and snowy too, but you start to see signs, although subtle (more sunshine, snow melt), that the weather is going to change. In March, temps begin to moderate gradually throughout the month.