Is the current warmth unprecedented?

The UK has been experiencing a run of very mild temperatures this month so far. Temperatures have been in double figures Celsius by day and often by night too for many areas. There have been exceptions, with snow across the hills of northern England and Scotland last weekend, and sub-zero values in the Highlands.

But given the dominant synoptic patterns have brought regular south to south-westerly winds, it comes as no real surprise that we are basking in ‘unseasonal’ warmth, as we did too for much of November.

Of course, we are only half-way through the month, so talk of a record warm month is somewhat premature, but with the week up to Christmas looking likely to bring more mild weather, I had a look at the stats to see how we stand with UK history.

According to official UK mean temperature data available from the Met Office, the mean temperature nationwide for this December up to the 14th was 7.1C (+3.2 above the 30 year mean).

The warmest Decembers for the country as a whole are as follows (since 1910):

Year      Temp      Anomaly (relative to 1981-2010 means)
1934       6.9        +3.0
1988      6.6        +2.7
1974      6.5         +2.6
1924      6.1         +2.2
1953      6.1         +2.2
1971       6.0        +2.1
1942      5.8        +1.9
1921       5.7        +1.8
2013      5.7        +1.8

The daily temperature records for December also show that warmth has been recorded well into the past, with an absolute high of 18.3C from 2nd December 1948 in the Scottish Highlands, obviously a result of strong foehn effects.

The record for England is 17.7C from both 1985 and 1994, whilst Wales is 18.0C from 1972. Northern Ireland is 16.0C from 1994.

There is clearly a wide spread of years with mild Decembers in the UK record. A glance through the archive charts from these years unsurprisingly shows prevailing winds between west and south for throughout the majority of these months.

Should this year break the monthly record, it would follow closely behind the record cold December of 2010, it poses the usual question, ‘is our weather becoming more extreme’? Add into the mix the examples of storms and floods from recent years and you can see why this is a hot topic.

The question though, is whether this mild spell is just like those of Decembers past, and a result of natural climate variability which has clearly happened before, or is it something which becomes more likely (or even warmer) due to changes in climate? Much to ponder, and only time will tell…