Frostbite in these extreme conditions can set in as quickly as three to 10 minutes, depending on age or exposure or other factors, such as wet gloves and socks, or even alcohol consumption, he said.
Colder than Alaska in some states
The brutally cold weather that's held millions in its frozen grip for days was so intense Thursday morning that 11 states in the continental United States hit a temperature lower than the one recorded in Alaska's northernmost city.
The Dakotas, Minnesota, Illinois, Iowa, Indiana, Michigan, New Hampshire, Wisconsin, New York and Pennsylvania all saw temperatures fall below -14 degrees, according to CNN meteorologist Taylor Ward. That was the temperature in Utqiagvik (also known as Barrow) a town of about 4,400 that sits north of the Arctic Circle.
But the end is in sight. The historic deep freeze that's killed 16 people will let up by the end of the week, according to CNN meteorologists.
At the cold's peak Thursday morning, about 7 a.m. ET, more than 216 million people saw temperatures below freezing, including 84 million who dealt with subzero temperatures, CNN meteorologist Dave Hennen said.
By the afternoon, about 30 million people were still under wind chill warnings and advisories -- down from a peak of 140 million in the morning.
But the misery will slowly melt away Friday, with a warming trend that could give many Americans thermal whiplash.
"Today is the last of the extreme cold air," Hennen said Thursday. "Temperatures will rebound quickly over much of the area that saw the extreme cold, creating a yo-yo effect of extreme temperature difference."
Chicago, for example, will see a temperature rise of almost 75 degrees -- from extreme cold of 20-25 below zero to temps in the low 50s on Monday.
And Atlanta, which has shivered in the 20s this week, will enjoy temperatures in the 60s when it hosts the Super Bowl on Sunday.
Chicago may have been hit with 'frost quakes'
Across the country, the bone-chilling weather has shattered dozens of records.