DENVER (CBS4) – States such as North Dakota, Minnesota, Wisconsin and Iowa are bracing for some of the coldest weather in years as we round out the month of January. Major cities, including Minneapolis, Milwaukee and Chicago, could see historic levels of cold by Wednesday with daytime highs staying in the teens and 20s below zero.

It’s all because of the polar vortex, a large area of very cold air that circles the North Pole. Some of that cold air is going to break off and slide south into the central United States this week.

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A map showing the polar vortex moving into the United States this week. (credit: CBS)

The National Weather Service is warning that wind chill values could exceed 50 below zero in many areas. Air temperatures in northern Minnesota and parts of North Dakota could approach 40 degrees below zero.

Eastern Colorado will sit on the extreme western edge of this air mass and will turn sharply colder starting Monday. By Tuesday morning we could be in the single digits above zero in Denver.

Chris Spears