Deep freeze grips US Midwest

A blast of icy polar air brought dangerously low temperatures to the US Midwest on Wednesday, causing at least three more deaths while halting mail delivery and forcing residents who pride themselves on their winter hardiness to huddle indoors.

Classes were canceled for Wednesday and Thursday for students across the Midwest, including Chicago, home of the nation's third-largest school system, and police warned of the heightened risk of accidents on icy highways. Michigan said all state offices would remain closed through Thursday.

At least a dozen deaths related to extreme cold weather have been reported since Saturday in Michigan, Iowa, Indiana, Illinois, Wisconsin and Minnesota, according to officials and media reports.

Boiling water freezes as it is thrown during subzero temperatures in Chicago. Photo: Reuters

Streets in Chicago were nearly empty, with few people walking outside in the painfully cold air as temperatures hovered around 18 degrees below zero Fahrenheit (minus 28 Celsius).

In Minneapolis, chilled to minus 14 F (minus 26 C), Brian Pierce ventured out to "embrace the elements" and found himself watching cars slipping on the roads.

"The roads sound really weird, it seems there's a lack of grip," he said. "And my teeth hurt."

Wind-chill temperatures in parts of the Northern Plains and Great Lakes plunged as low as minus 42 F (minus 41 C) in Park Rapids, Minnesota, and to 31 degrees below zero F (minus 35 C) in Fargo, North Dakota, according to the National Weather Service (NWS). The frigid winds began to blow into the US East Coast later on Wednesday, sending temperatures plunging there.

More than a thousand flights, close to two-thirds of those scheduled, were canceled on Wednesday into or out of Chicago O'Hare and Chicago Midway international airports, according to the flight tracking site FlightAware.

The Amtrak passenger rail service canceled all trains in and out of Chicago on Wednesday.

The bitter cold was caused by a displacement of the polar vortex, a stream of air that normally spins around the stratosphere over the North Pole but whose current was disrupted and was now pushing south.

Officials opened warming centers across the Midwest, and in Chicago, police stations were open to anyone seeking refuge. Five city buses were also deployed to serve as mobile warming centers for homeless people, while city police handed out hats, jackets and blankets.