Washington, Jan 29 (IANS): A Polar Vortex will hit the US Midwest, which will cause extreme low temperatures that could shatter records and plunge much of the region into its deepest freeze in decades, according to forecasters.

The Polar Vortex is a brutal mass of cold air within strong bands of circulating winds. It has spread southward from its normal location near the North Pole in recent weeks, bringing arctic weather to the middle of the US, The New York Times quoted the forecasters as saying on Monday.

Wisconsin Governor Tony Evers declared an emergency on Monday and told the National Guard to be ready to help.

The University of Notre Dame announced it was closing its northern Indiana campus from Tuesday evening until Thursday afternoon. In Chicago, city leaders deployed buses as mobile warming centres and offered tips on how to thaw frozen pipes.

Forecasters expect Wednesday's high temperature to be minus 25 degrees Celsius in Chicago and Minneapolis.

If the forecast holds, that would be Chicago's lowest high temperature for a single day since officials began keeping records.

"This is what you would expect when you get into central and northern Canada," said Brian Hurley, a National Weather Service meteorologist.

In Milwaukee, St. Paul and Minneapolis, public schools called off Monday classes. Governor Gretchen Whitmer of Michigan sent most state workers home early.

The Midwest region comprises Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Ohio, South Dakota and Wisconsin.