I know that the original post was last year but I thought that this addition would be of some interest.
I found the post while googling for any details of January 1795, for reasons which will become obvious.
I developed a computer program which correlates daily CET figures for recent months with past months in the series. When I ran the figures for December 2009 (using provisional daily figures), I was surprised to find that the closest match was December 1794, with a correlation of 0.706. Actually, with a provisional figure of 3.3c, this December was colder than December 1794 which had a mean figure of 3.7c.
I was also surprised to find that December 1794 was followed by, the coldest month on record in the CET series. i.e. January 1795. Of course this doesn't mean that January 2010 will be as cold but it may point to a colder than average month.
I am still interested in finding out why January 1795 was so cold, so if anyone has any information on this, I would be grateful to hear it. Unfortunately since minimum figures are not available for 1795, it is impossible to know how cold it really was but with mean figures for most days well below zero, minimum figures must have been very low, so presumably there were special circumstances surrounding that month, which are unlikely to be repeated this year.
