Christmas

For some reason weather types occasionally seem to flip over the Christmas period, a cold spell at Christmas can sometimes come to an abrupt end by New Year, and sometimes what looks like a milder Christmas, can suddenly give way to much colder weather as we get into the New Year. Out of curiosity, and with nothing much else to do on a rainy day, I decided to duplicate and refactor my Christmas viewer to produce mean anomalies (or temperatures) from the CETCET Central England Temperature daily series for the periods before (22nd to 28th December), and after (29th December to 4th January) to see what I could find.
As you can see from the results, Christmas 1866 was one of the most schizoSchizo A combining form from the ancient Greek meaning 'I split'. Christmases Central England has seen since 1772, starting mild, with anomalies of +2.1°C, but becoming very cold, with anomalies of -6.5°C into the New Year.
The Christmas of 1796 was another classic, this time starting very cold, with anomalies of -8.1°C, but then turning much milder with anomalies of +1.4°C into the New Year.
The most recent example of a schizo Christmas in Central England was that of 2010, Christmas that year was very cold, with anomalies of -6.8°, but New Year, although still cold was much milder than Christmas, with anomalies of -1.0°C.

I revisited some code I wrote many years ago and smartened it up a bit, it fills a grid with mean temperatures and anomalies for the Christmas period (21 December to 4th of January) from the daily CETCET Central England Temperature series which started in 1772. It simply calculates a mean temperature and anomaly for each year for that period and then adds it to the grid.
The coldest Christmas by far was that of 1870 with a mean temperature of -3.6°C and anomaly of -8.1°C. All the cold Dickens Christmases of 1853, 1860, 1890 & 1892 are in top 20. One unusual cold Christmas that I noticed was the forgotten Christmas of 1961 (#4), which surprisingly was fractionally colder than that of 1962 (#8). The most recent cold Christmas besides those were the ones in 1992 (#18), 1996 (#19), 2010 (#20) and 2009 (#31).
The mildest Christmas since 1772 in Central England was that of 2015, which just edged 2023 from the number one spot, with a mean temperature of 8.7°C, which was 4.2°C above the 1991-2020 LTALTA Long Term Average. This is usually defined as a 30 year period by the WMO.. Five Christmases from the 21st century feature in the top ten mildest since 1772.
The coldest Christmas day was that of 1796 (-10.8°C), the mildest 2023 (10.7°C). All in all a fascinating little addition to my Daily CET application. I’ll give you two guesses to where this one will end up.