Wisconsin Initiative on Climate Change Impacts (WICCI)

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Wisconsin’s location in the interior of North America and the lack of mountains to the north and south expose the state to incursions of bitterly cold air masses from the Arctic in the winter and warm, humid air masses from the Gulf of Mexico in the summer, causing a large range of temperatures across the state. The southern part of the state experiences cold winters and mild to hot summers, while the northern part of the state experiences frigid winters and generally cool summers with brief bouts of excessive heat. The winter season is dominated by dry and cold air, with occasional intrusions of milder air from the west and south. The summer is characterized by frequent warm air masses, either hot and dry continental air masses from the arid west and southwest or warm and moist air from the south. However, periodic intrusions of cooler air from Canada provide breaks from summer heat. The state has borders along Lake Superior to the north and Lake Michigan to the east, and the proximity to the lakes provides a moderating effect on temperatures for locations along the shorelines. Annual average temperatures vary from 39°F in the north to 50°F in the south.