Extreme cold has a unique ability to render survival dependent on uninterrupted energy supplies. A power outage during a heat wave, while dangerous, generally poses less of an immediate threat than one during an Arctic blast. You can survive without air conditioning longer than you can survive without heat in sub-zero temperatures.

A potent cold front will enter the north-central U.S. before roaring across much of the rest of the nation over the weekend.

Bitterly cold air that originated in Siberia will arrive in the U.S. in the coming days, resulting in dangerously cold wind chills for millions of Americans.