In any other decade a December as bad as 2019 would be the standout worst one but it says it all that the 2010s has four close competitiors in 2013, 2015, 2016 and 2018. 

At least all of those apart from 2018 saw some snow and didn't consist of day after day of 5-6C, wind and/or rain which has been the case in December 2019. Nothing of interest whatsoever. A totally worthless winter month from every conceivable viewpoint.