Switzerland will mark its warmest December since the country that founded winter tourism began keeping records 150 years ago.

Clear skies and dry ground have seen the Alpine nation end the year 3.4 degrees Celsius above the long-term historical average for December, a climatologist for the Federal Office of Meteorology and Climatology (MeteoSwiss) said on Monday.

"There's no doubt about it," Stephan Bader said. "It's the warmest December in our recorded measurements dating back to 1864 — clearly. And it's especially pronounced at higher altitudes."

The dry warmth and slopes bereft of snow have hurt resort owners and ski lift operators, who are already contending with Switzerland's strong currency discouraging foreign visitors.

MeteoSwiss earlier this month said it expected 2015 to break the annual record for the third time in just a handful of years.

Globally, this year will be the warmest on record and 2016 could be even warmer due to the El Niño weather pattern, the World Meteorological Organization said last month. It warned that inaction on climate change could see global average temperatures rise by 6 degrees Celsius or more.