January 1795 at -3.1 is the coldest month in the entire CET series with only 1684 (-3), 1814 (-2.9) and 1740 (-2. coming close. The mean January CET for 1761-1790 was 2.2 (a full 2c below the 1971-2000 mean and a potent reminder of the severity of many winters during the 'Little Ice Age'). Thus January 1795 was an astonishing 5.3 below the 1760-1791 mean. Nonetheless even though January 1963 at -2.1 was a full 1.0 less cold than 1795 its' anomaly from the 1931-1960 mean of 3.5 was an even greater 5.6.
The CET for January 1796 was 7.3 (joint second mildest with 1921) and the 5th coldest month of the year. Whilst 1916 holds the record for the mildest January at 7.5, 1796 stands out as being the mildest January relative to the immediately preceding 30 year mean of 2.2. Thus January 1796 was 5.1 above the then 30 year mean. To put this in context, in this decade we would need to record a January CET of 9.3 to equal the anomaly...
A difference of 10.4 between the same month in successive years is unprecedented in the CET series.
A useful reminder too that there will always be variations, sometimes very considerable, around any mean temperature and that the temptation to invest individual monthly data with undue significance should be avoided.
regards
ACB
[data from UKMO Hadley]
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.
The Anomolous Januaries of 1795 and 1796
in Historic Weather
Posted
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.