Arctic weather pattern keeps cities below zero

Millions of Americans are waking up to another day of bitter cold.

The National Weather Service forecast for Monday a high of -19 degrees Fahrenheit in Fargo, North Dakota, -17 degrees in Minneapolis, Minnesota, and -11 in Chicago.

(SOUNDBITE) (English) DR. BECHARA CHOUCAIR, CHICAGO DEPARTMENT OF PUBLIC HEALTH, SAYING:

"The cold temperatures we are expecting this coming week are more than an inconvenience. They are serious, they are dangerous and they can cause a serious health risk."

A polar vortex is pushing Arctic air farther south than usual, bringing the Midwest its lowest temps seen there in two decades.

Officials closed all public schools in Minnesota as well as in Chicago.

More than 7,300 flights have been delayed and 3,500 canceled across the country.