Current five year rolling averages are:- February 4.9C December 5.2C January 5.8C The January figure is the highest in the CET series, having previously peaked at 5.4C in 1737. I was surprised to find that the five year rolling mean for February fell to 1.9C in 1987, the lowest five year period since before 1700 when the temperature readings are to the nearest 0.5C, and presumably not so reliable. The five year rolling mean to January 1943 came in at 1.8C, the coldest January period of the 20th century, however Januarys have been through much colder spells than this, being as low as 0.6C for the 5 years to 1815, and 0.8C upto 1780. It seems that January really is the month that's put in the most warming historically, and is presumably therefore the month with the most potential for cooling off again at some point.