Sub-zero temperatures, strong winds and heavy snowfall create huge ice caves at Lake Michigan, seen Feb. 19, 2014. More:Rare frozen ice path to dazzling caves(John L. Russell / Associated Press)
Niagara Falls, as seen from the Canadian side in early January, were an icy spectacle with the polar vortex. (Nick LoVerde / Associated Press)
Ice floes fill the Hudson River as the New Jersey waterfront is seen at sunset on Jan. 9, 2014, in New York City. A polar vortex descending from the Arctic caused the floes to form. MORE:What is a polar vortex and what is it so dangerous?(Afton Almaraz / Getty Images)
