Polar Vortex

Ice builds up along Lake Michigan at North Avenue Beach as temperatures dipped well below zero in Chicago, Ill., Jan. 6, 2014.

Chicago hit a record low of -16 degree Fahrenheit as a polar air mass called a "Polar Vortex" brought the coldest temperatures in about two decades into the city.

Credit: Getty Images

Polar Vortex

In this satellite handout image provided by National Oceanic and Atmospheric Administration (NOAA), shows the entry of a large area of low pressure, from the Polar Vortex, into the Northern U.S., Jan. 6, 2014.

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Polar Vortex

Passengers heading into downtown wait on an "L" platform for the train to arrive in below zero temperatures, in Chicago, Jan. 7, 2014.

Platforms were crowded and trains were delayed because doors on the trains kept freezing open. Chicago experienced its third consecutive day of below zero temperatures.

Credit: Gerry Images

Polar Vortex

With temperatures at about 22 below zero with a -50 windchill, it was hard to find the beauty in the brutal weather in Bismarck, N.D., Jan. 5, 2014.

Sundogs, a ring of light visible around the sun or moon when light is refracted through ice crystals in the atmosphere, are quite beautiful along Highway 83 north of Bismark.

Credit: AP

Polar Vortex

Ryan Metcalf tries to hang on to his golden retriever, Daisy, in Brentwood, Mo., Jan. 5, 2014.

Credit: AP

Polar Vortex

The Tidal Basin freezes over near the Jefferson Memorial in Washington D.C., Jan. 7, 2014.

Credit: Gary Cameron/Reuters

Polar Vortex

U.S. Postal Service letter carrier Jamie Jasmon struggles through snow and below zero temperatures while delivering the mail, in Springfield, Ill., Jan. 6, 2014.

Credit: Seth Perlman/AP

Polar Vortex

Commuters make a sub-zero trek to offices in the Loop in Chicago, Illinois, Jan. 6, 2014.

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Polar Vortex

Michael Stanton walks between houses covered in ice from sea spray along the shore in Scituate, Mass., Jan. 3, 2014.

Wind-whipped, fluffy snow continued to fall across the state, buffeted by wind gusts at around 40 miles per hour. National Weather Service reported Friday morning that the temperature in Boston was 2 degrees, but 20-below when the wind chill is factored in.

Credit: Michael Dwyer/AP

Polar Vortex

Marguerite Johnston uncovers her car in Grosse Pointe, Mich., Jan. 6, 2014.

Credit: Paul Sancya/AP

Polar Vortex

Hank Wade is bundled up as he clears snow from a sidewalk in Lyndhurst, Ohio, Jan. 6, 2014.

Credit: Tony Dejak/AP

Polar Vortex

A man wears a face mask and heavy clothes while walking through downtown Springfield, Ill., in blowing and falling snow as a strong winter storm moves through the Midwest, Jan. 5, 2014.

Credit: Seth Perlman/AP

Polar Vortex

Mist rises from Lake Michigan as temperatures dipped well below zero, in Chicago, Jan. 6, 2014.

Credit: Scott Olson/Getty Images

Polar Vortex

A woman bundled against the cold walks past a homeless man in McPherson Square as temperatures dipped into the single digits Fahrenheit and minus degrees with the wind, in Washington, D.C., Jan. 7, 2014.

Credit: Karen Bleier/AFP/Getty Images

Polar Vortex

A sculpture near a walking path is covered in snow in Carmel, Indiana, north of Indianapolis, Jan. 6, 2014.

Credit: Brent Smith/Reuters