In an extraordinary event precipitated by a huge North Atlantic storm system, the North Pole has just experienced a short burst of above zero air temperature (green in this plot). Polar temperatures through the 24 hour darkness of the long arctic night are usually nearer minus 30 °C.
US GFS weather model predicted surface air temperature for 06:00z on 30 December 2015, as plotted by Climate Reanalyzer
It’s not clear yet whether this event is unprecedented. Data is scarce of course, but far from non-existent — for many years a network of ice buoys has monitored arctic conditions. Here is the air temperature record from a buoy close to the pole on the North Atlantic side:
Ice buoy air temperature data, from IABP
Air temperatures were close to 0 °C back in early November, but that’s not midwinter*.
(* The midwinter solstice was on 22 December.)
