The temperature at TF Green is running more than 4° above normal this December. While very mild, that is actually below the December temperature anomaly for the country as a whole. Through December 16, the contiguous United States had a 3.516° C temperature anomaly – that is an astounding 6.3° F warmer than normal. The map below shows the core of the warm air centered over the Midwest, with some areas averaging about 10° F above normal so far this month.
It is definitely worth noting that the United States has been one of the warmest places (relative to normal) on the planet so far this month. In fact, the global average temperature is just about normal for the month. The extremely mild air in the U.S. is being balanced out by some very cold air over Western Canada, Alaska, and Russia. It has also been a chilly December in Europe.