On Wednesday, December 10, 2014 1:53:07 PM UTC, Scott W wrote:
After being reminded about this a couple of weeks ago I decided to have a look at the stats back to 1806 and see what the results are.

If there is a run of cold days (3.3C or less) around mid-month the chance of an average to colder than average January and February is 94% and 74% respectively. The chance of an average to colder than average March is 96%. Also notable is that the chance of a severe spell in January (4C colder than normal) is 30%.

The full blog post can be found here. http://wp.me/p2VSmb-wO

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Interesting as far as it goes - but what temperature is this? CET? Or one location's maximum temperature? Or 24-hour average?

In any case it looks like being slightly milder just after mid month. If the measure is maximum temperature I don't at see that below 3 or 4 deg C for most.

It makes a kind of sense because mid Dec-Jan regimes are often linked, so a cold block, for example, in mid December would more often than not also be January's characteristic.

Stephen.