We are having a very hard winter, but it has only been three weeks long. Before Jan. 21, there had been just one serious snowstorm on Dec. 27, and hardly any snow before that. Temperatures had been humming along well above average under the influence of El Niño until the polar vortex disruption came along.
Last winter was also rather back-heavy. Only 17 inches of snow had fallen through today's date last year. But another 33 inches fell after Valentine's Day, with much of that falling in March. A very cold pattern the first half of April delayed snow melt until very late in the spring. It is not unusual for a winter season to suddenly change or even reverse character, as various elements affect the position of the jet stream and storm track.