On Jan 7, 7:35*pm, "Col" wrote:
Graham Easterling wrote:
On Jan 7, 5:34 pm, "Ian Bingham"
wrote:
My average temperature graph for January (1990-2010) shows low
temperatures at the beginning and end of the month and relatively
high temperatures at mid-month. This appears to be due to the fact
that every year in January we seem to get a few days of more or less
strong SWlies which of course raises the temperature appreciably.
This has occurred at various times of the month, so the average puts
it in the middle, I suppose. For example I have as 21-year means:
Jan 1st 2.1C
Jan 15th 4.4C
Jan 31st 2.3C

Ian Bingham,
Inchmarlo, Aberdeenshire.

A very similar pattern here over the 20 years of my records. In fact
the 15th is the mildest day of the month with a mean temperature of
8.2C.

There are marked colder spells each side, the low points being:-

8th *6.7C
26th 6.2C - The coldest day of the winter over 20 years.

OK, so examples from two very different areas, can we
extrapolate from these two points that this is a countrywide
phenomenon
I've heard of the 'mid-December mildening' but not January.
--
Col

Bolton, Lancashire
160m asl

Nonetheless in central southern England mid January has from memory
been almost unfailingly mild every year since 1988.
If one looks at wetterzentrale.de, some "mild" type or other, either
zonal or SSW winds, was present on Jan 15th on all but 4 years since
1988 - the exceptions being 1991, 1992, 2000 and 2001, which agrees
with my memory.

Over the same period, 25th Jan showed a "non mild" type (by my
interpretation of the charts) in 11 of the years since 1988, but 5th
Jan seems to have been almost equally mild with a mild type in all but
5 of the years. Until 2009/10, early Jan seemed to be equally prone to
mild weather in recent years as mid Jan, but a change of type does
seem to occur quite often later in the month.

Nick