On 1 Oct, 09:54, John Hall wrote:

That led me to wonder what the highest mean pressure is for (a)
September and (b) any month in the UK. (I suspect that January and
February might feature strongly in the latter category, winter Highs
tending to be more intense.)

Heathrow's highest Sept mean was 1024.1 mbar in Sept 1941. The highest
monthly mean in London/SE England for any month back to 1930 has been
Feb 1959, 0900 GMT means 1033.2 mbar at LHR, 1033.1 mbar at Kew,
1033.3 mbar at Gatwick. My personal highest in this area (records
since 1980) has been 1031.8 mbar in Feb 1993.

The highest monthly mean MSL pressure on record for the British Isles
that I'm aware of was 1035.4 mbar at Malin Head at 07h in Ireland in
February 1932 (mean at 13h was 1035.9 mbar). Mean pressure at 07h in
Feb 1932 exceeded 1030 mbar across the whole of the British Isles; the
lowest anywhere in BI during the monrth was 1014 mbar.

A 30 day mean split across January and February 1932 would probably
have slighly exceeded 1036 mbar, because on 26 January the barometer
reached 1051.0 mbar at Stonyhurst, Lancashire, at Sheffield and at
Meltham (West Yorkshire), 1050.4 mbar at York and 1050.3 mbar at
Sealand, Cheshire (the most recent occasion on which the barometer has
exceeded 1050 mbar anywhere in England), while 1047.4 mbar was
attained on 20 February at Inchkeith, Renfrew and Donaghadee.

More details and maps in my paper on intense anticyclones in Weather,
February 2007.

--
Stephen Burt
Stratfield Mortimer, Berkshire