A Filipino worker arranges roasted pigs which they sell in suburban Quezon city, Philippines on Tuesday, December 23, 2014. Roasted pig is popular during Filipino celebrations and traditionally served during a Christmas eve dinner called “Noche Buena” in this predominantly Roman Catholic nation. (Photo by Aaron Favila/AP Photo)

A woman looks at a swimmer getting herself warm after the annual Christmas winter swimming competition in the Vltava river in Prague December 26, 2014. (Photo by David W. Cerny/Reuters)

The rising sun penetrates early morning mist and begins to burn off the first frost of winter in the Cheshire countryside at dawn on 24 October, 2007, Knutsford, England. (Photo by Christopher Furlong/Getty Images)

People dressed in swimsuits participate in the BoogelWoogel alpine carnival at the Rosa Khutor Alpine Resort in Krasnaya Polyana, Sochi, Russia on April 1, 2017. (Photo by Artur Lebedev/TASS)

A woman from the Tarahumara ethnic group cuts firewood with an ax while preparing for winter in Caborachi village, in Guachochi, Mexico, December 17, 2016. (Photo by Jose Luis Gonzalez/Reuters)

Bison along the Bitterroot Valley's Eastside Highway north of Stevensville, Montana, are covered in snow following a blizzard on November 23, 2010. (Photo by Perry Backus/The Missoulian)

A monarch butterfly rests on a visitor's hand at the Monarch Grove Sanctuary in Pacific Grove, California December 30, 2014. Monarch butterflies may warrant U.S. Endangered Species Act protection because of farm-related habitat loss blamed for sharp declines in cross-country migrations of the orange-and-black insects, the U.S. Fish and Wildlife Service said. (Photo by Michael Fiala/Reuters)

A woman toes a tube carrying a man during the Ice and snow carnival at Taoranting park in Beijing, China, January 25, 2016. (Photo by Kim Kyung-Hoon/Reuters)