The first half of December had an average temperature of 21.2 degrees which is nearly 5 degrees above average. It was the 37th warmest such stretch since 1881. Last year the first half of December averaged about 1 degree warmer so this has been the second straight mild December (at least for now).
That was definitely not the case from 2007 to 2010. All four of those Decembers started cold and finished cold. Those were also very snowy Decembers with all of them ranking in the Top 10 snowiest on record with December 2008 ranked as the snowiest December since snow records began. It was the abundant moisture from those four months that also set the stage for the flooding that occurred the following springs.
Although the second half of this month may trend colder, it is highly unlikely we will experience anything like we did during that stretch.