A walker has left a handprint on a snow- covered tree trunk on Grosser Feldberg mountain in the Taunus mountain range, Germany, 16 January 2017. (Photo by Frank Rumpenhorst/DPA)

A man smiles as he carries firewood he bought on a street amid ongoing fuel and cooking gas shortages in Yemen's capital Sanaa December 2, 2015. (Photo by Khaled Abdullah/Reuters)

Fog hangs between pine trees in a forest near Neubrueck, eastern Germany, on November 20, 2012. Meteorologists forecast cloudy sky and temperatures around 5 degrees Celsius for the region. (Photo by Patrick Pleul/AFP Photo)

Starlings come home to roost on Brighton's Old Pier as the sun sets on December 21, 2011 in Brighton, England. December 21 marks the winter solstice, the shortest day of the year. (Photo by Dan Kitwood/Getty Images)

Visitors watch as Grigory Broverman, a member of the Cryophile winter swimmers club, pours a bucket of cold water over his 6-year-old daughter Liza during a flash mob, part of a celebration of Polar Bear Day at the Royev Ruchey Zoo in a suburb of the Siberian city of Krasnoyarsk, Russia, November 29, 2015. The air temperature was around minus 5 degrees Celsius. (Photo by Ilya Naymushin/Reuters)

A combination picture shows Will Adam, 14, snowboarding down a street on Beacon Hill during a large winter blizzard in Boston, Massachusetts, United States January 27, 2015 (top), and a woman looking at her phone as she walks down the same street June 13, 2015. Outdoor scenes in Boston show local residents enjoying balmy weather amid lush greenery as the summer solstice approaches on 21 June. The very same locations suffered heavy snowstorms last winter, with snow ploughs, skiers and snowboarders battling the drifts. Boston got 275.8 cm of snow over the winter, the most since 1872, when records began. A few months after the snowstorms, Brian Snyder revisited the same places and shot pictures at exactly the same locations. (Photo by Brian Snyder/Reuters)

Cameron Shonnard backflips a jump at Squaw Valley in Olympic Valley, California, December 5, 2015. An El Nino is forecasted for California, and regular precipitation has been welcomed after years of drought. (Photo by Max Whittaker/Reuters)

Ice covered leafs are pictured on a tree near Amstall in northern Austria, December 2, 2014. Freezing fog and rain covered parts of the region with ice, causing blocked roads due to fallen trees and closed schools for security reasons, local media report. (Photo by Heinz-Peter Bader/Reuters)