The human memory is not very reliable at calculating trends from the past. This has something to do with extraordinary events often crowding out uneventful ones – and standing out. As time progresses the extraordinary events tend to get overly weighted and distort the memory.
Balz Rittmeyer and Marc Fehr at this site here present a couple of charts from the Swiss Meteorological Office depicting the frequency of white Christmases (December 24-26) occurring in Zurich, Switzerland, putting to rest the often asserted claim “we don’t get white Christmases like we used to“.
The following chart uses green trees to depict snowless Christmases, white trees to depict white Christmases, and half green/half white to show Christmases where at least one day had at least 1 cm of snow.
Source: Meteo Schweiz
Rittmeyer and Fehr write:
Is climate change to blame for seldom occurrence of white Christmases nowadays? No. A look at the statistics shows that in earlier times there wasn’t more often snow on December 24, 25 or 26.”
Zurich is located at the base of the Alps at some 400 meters above sea level. Clearly in the 1930s Zurich saw a number Christmas holidays with snow on the ground. But note how in the 1940s Zurich saw 9 consecutive Christmases in a row without snow – by far the record. This year it appears that Zurich will reach 5 years in a row – yet still far short of the 1940s record. Arguably the last 15 years have been a bit on the light side, but so was the period from 1941 – 1960.
First 1843 London Christmas cards depicted no snow
Rittmeyer and Fehr also write that the misconception of more frequent snowy Christmas days is in part due to early idyllic postcard and book images of Christmas, such as those we often see on today’s Christmas greeting cards. They report that the first Christmas cards printed in London in 1843 showed no snow (citing Swiss climate scientist Stefan Brönnimann). It wasn’t until later, beginning in 1860, after Englishmen started spending the Christmas holidays in the Swiss mountains did images of snow appear on greeting cards in London.
Also analyses of snow on Christmas day in Germany also show no trend as well.