This June was the wettest since records began, with double the average rain falling during the month, the Met Office said.
Provisional figures showed the UK received 145.3mm (5.7 inches) during June - beating the previous record of 136.2mm (5.4 inches) seen in June 2007.
It is the second month this year to see record-breaking amounts of rain, after this April became the wettest in the records dating back more than a century to 1910.
June saw long, prolonged rainfall and short but exceptionally heavy showers, and ended with freak storms which battered areas of the Midlands and the North East.
The exceptional amount of rain caused floods in Wales and parts of England.
Looking at individual countries, it has been the wettest June on record for Wales and Northern Ireland, the second wettest in England, and the eighth wettest in Scotland.
Many areas have seen extremely high rainfall - with 83 (out of 237) observation sites marking their wettest June on record. Some of these aren't significant as they have very short recording histories, just a year in some cases, but others have been operating much longer - Otterbourne in Hampshire been operating for 119 years.
One of the key features of the month has been that the far north west of the UK, traditionally the wettest part of the country, has been remarkably dry.
Up until quite late in the month, a few stations in this area were below their record lowest rainfall amounts - but they just missed the record books with rain falling in the last few days of the month.
Current or previous wettest years on record are:
UK: (Previous) 136.2 mm in 2007
England: 146.0 mm in 2007
Wales: (Previous) 183.1 mm in 1998
Scotland: 155.0 mm in 1938
Northern Ireland: (Previous) 152.6 mm in 1912.
Average UK conditions (1971-2000):
Mean temperature 12.6 deg C
Rainfall: 72.6 mm
Sunshine: 169.4 hours