It is interesting to point out that the other warmest years on record do still manage to sneak in a below average month. 2022 being the warmest year, but still managing a below average December would actually be following the trend.
Further to this, there have been been 10 years with 11 above average months, before 2022, but no year so far has managed a clean sweep.
The years with 11 above average months were 1781, 1834, 1945, 1949, 1999, 2003, 2006, 2014, 2017, and now 2022.
The current run of above average months started in June 2021, a total of 18 months so far, which look like it's the longest streak in the CET record. The previous record was the 15 months from April 2006 - June 2007.
(This is based on the 1961 - 1990 average used by the Met Office.)