The wettest September on record for England and Wales is 1918 with 189.5mm or 7.46 inches (247%). It was also  a very cyclonic month, 2nd most cyclonic September on record.

Here are some rainfall data for this month

Camden Square: 5.68" (284%)
Tenterden: 6.26" (278%)
Arundel: 7.46" (289%)
Oxford: 4.58" (230%)
Bury St Edmunds: 5.88" (270%)
Launceston: 8.40" (270%)
Church Stretton: 7.34" (306%)
Boston: 4.21" (207%)
Southport: 8.49" (274%)
Wetherby: 6.95" (329%)
Newcastle: 5.30" (265%)
Cardiff: 10.69" (296%)
Llandudno: 6.95" (279%)
Cargen: 7.29" (218%)
Glasgow: 6.32" (211%)
Dundee: 3.85" (164%)
Aberdeen: 4.42" (164%)
Fort William: 7.88" (119%)
Waterford: 7.97" (250%)
Dublin: 4.87" (236%)
Omagh: 7.18" (211%)


The 29th was an unusually cold day for September with maxima barely reaching double figures in many places. Hereford recorded a maxima of just 7C that day and temperatures fell further and sleet was reported as low down as 800ft in the Black mountains, while above 2300ft it was six inches deep in places.

The CET for the month was 11.9, so it was a very cool and exceptionally wet month.

Think of the Flanders mud and the poor guys in the trenches. It appears to have been a feature of WWI that it was a wet period across NW Europe.

Amazing - i thought September 2000 was the wettest September. The autumn of 2000 was amazing for rain.