While part of North America is suffering through a record freeze, northern Europe is enjoying unusually balmy temperatures that are disturbing wildlife, traffic and the winter sports season.
The month of December was one of the mildest in a century in the Nordic countries, according to meteorologists, with temperatures exceeding their normal seasonal average by four to five degrees Celsius (24 to 30 degrees Fahrenheit) in Norway and Finland.
Oslo experienced its warmest Christmas since records began in 1937, while in Helsinki and southern Finland the second half of December was the mildest in 30 years. In Koege outside Copenhagen the mercury reached 11.6 degrees C (52.9 F) on Christmas Eve.
This year began in a similar vein: pavements in all the Scandinavian capitals were uncharacteristically free of ice and snow, with the white stuff appearing only briefly in Oslo and Stockholm in early December.
Swedish daily Dagens Nyheter said several types of migratory birds have yet to leave for warmer climes, and showed cherry blossoms that normally only appear in the spring.
"In the north, winter has arrived, but in the south it's autumn according to the meteorological definition," the Swedish Meteorological and Hydrological Institute (SMHI) said.
On Norway's west coast, local newspaper Sunmoereposten published reader photographs of crocuses, daisies and dandelions, and budding branches of honeysuckle.
The lack of snow forced the organisers of the Norway Ski Championships, held in mid-January, from the town of Molde to the more reliable location of Lillehammer, which hosted the 1994 Winter Olympics.
In Finland, the snow-free weather is worrying the organisers of the cross country skiing championships set to be held in Vantaa from January 17 to 19, amid fears that it may be too warm to cover the trails with artificial snow.
In Denmark, outdoor skating rinks designed to withstand temperatures of 5 C (41 F) were covered with water this week.
Finnish roads were rapidly deteriorating due to the constant shifts between sub-zero temperatures during the night and warmer weather during the day, Jukka Karjalainen, director for road maintenance at the Finnish Transport Agency, told daily Helsingin Sanomat.
Without any ice to protect them, they were also being worn down by winter tyres, he added.
The mild weather is caused by the same low-pressure area that has plunged large parts of the US and Canada into an unprecedented freeze.
"The link between the cold in North America and the mild temperatures here can be traced to a low pressure area that gave North America cold winds from the north, but which sent warmer winds from the southwest this way," said Reidun Gangstoe, a researcher at the Norwegian Meteorological Institute.
However, meteorologists predict temperatures will be closer to their seasonal average by the end of the week, when colder air is set to come in from Russia.