Michigan has a humid continental climate throughout the state, although there are two distinct regions. The southern and central parts of the Lower Peninsula (south of Saginaw Bay and from the Grand Rapids area southward) has a warmer climate with hot, humid summers and cold, but shorter winters. The northern part of Lower Peninsula and the entire Upper Peninsula has a more severe climate, with warm, humid but shorter summers and long, cold to very cold winters. Some parts of the state averaging high temperatures below freezing from December through February, and into early March in the far northern parts. During the late fall through the middle of February the state is frequently subjected to heavy lake effect snow. The state receives a good amount of precipation throughout the year, averaging from 30-40 inches annually. Typically, from December through March is slightly drier, while July through September is slightly wetter than the rest of the year, although this difference isn't extreme as in some other states.
The entire state averages around 30 days of thunderstorm activity per year, and these can be severe, especially the further south in the state one goes. The state averages 17 tornadoes a year, and these are much more common in the extreme southern portion of the state with portions of the southern border nearly as vulnerable historically as parts of Tornado alley. Further north, in the Upper Peninsula, tornadoes are rare, but have occurred.