The primary winter months of December, January, and February averaged over the contiguous 48 United States were the 2rd coldest winter in the last 35 years. The average temperature of 32.2 deg. F was barely edged out by the slightly colder winter (32.0 deg. F) of 2009-2010.
The analysis is based upon ~350 NOAA/NWS stations that measure temperatures every 6 hours (or more frequently), many located at airports. The data I use are adjusted for average spurious urban heat island (UHI) warming that increases with population density around the thermometer site. That relationship is shown at the end of this article.