These are CET daily mean temps in degrees Celsius for the 3 winter
months over the period 1772-2007 (2006 in the case of December).

Jan Feb Dec
1 3.29 3.92 5.11
2 3.30 3.86 5.02
3 3.18 3.99 5.05
4 3.38 3.99 5.08
5 3.23 4.07 5.14
6 3.36 4.11 4.80
7 3.18 4.23 4.59
8 3.21 3.98 4.36
9 3.35 3.93 4.17
10 3.43 3.92 4.27
11 3.28 3.80 4.18
12 3.04 3.71 4.37
13 3.28 3.63 4.49
14 3.31 3.72 4.49
15 3.19 3.97 4.39
16 3.34 3.89 4.32
17 3.34 3.74 4.42
18 3.30 3.73 4.38
19 3.44 3.76 4.06
20 3.29 3.73 3.93
21 3.48 4.14 3.94
22 3.56 4.33 3.87
23 3.50 4.45 3.82
24 3.51 4.40 3.77
25 3.39 4.48 3.44
26 3.46 4.45 3.41
27 3.62 4.59 3.41
28 3.54 4.50 3.40
29 3.72 - 3.64
30 3.79 - 3.59
31 3.96 - 3.44

I didn't bother with Feb 29th, as calculating the mean would have been
too fiddly to be worthwhile.

I've already commented on January in another post. February shows a
tendency to be a bit colder between about the 11th and 20th, giving some
credence to the Buchan cold spell (which the singularity work of Brooks
and Lamb I believe also identified). The last week is notably milder.

December shows a tendency for a relative cold period from about the 8th
to 12th. It then cools down again from about the 19th. There's no sign
of a post-Christmas mild spell, though, with the 25th to 31st being the
coldest part of the month. I suspect that the mean for the last 100
years only might show very different trends.
--
John Hall

"The covers of this book are too far apart."
Ambrose Bierce (1842-1914)