The August of 1917 was a washout, it is the 3rd wettest August on record for England and Wales with 172.0mm. (6.77 inches)
For Wales, it was 128% in excess of the average, England it was 94%, Ireland it was 81% and for Scotland it was 23%.
Some rainfall totals
Camden Square: 3.99" (167%), 23 days of rain
Tenterden: 6.4" (265%) 22 days of rain
Bury St Edmunds: 5.02" (199%) 23 days of rain
Stroud: 5.99" (207%) 24 days of rain
Boston: 4.47" (187%) 21 days of rain
Newcastle: 7.58" (237%) 29 days of rain
Cardiff: 7.9" (174%) 28 days of rain
Dundee: 5.56" (167%) 29 days of rain
Dublin: 7.58" (246%) 24 days of rain
The month went out with a bang when an unusually deep low crossed the UK
A pressure reading of 966mb was recorded by Charles Lewis Brook at 7.20am (GMT) on the 28th August at Harewood Lodge in Yorkshire.
The storm produced heavy rains, thunderstorms and severe gales in places.