Last month was the UK's wettest June since records began in 1910, provisional Met Office figures show.
It comes after this year also saw the rainiest April on record, while the period from April to June was the wettest recorded for the UK.
June was also the second dullest on record with 119.2 hours of sunshine - the record of 115.4 hours was in 1987.
Total UK rainfall was 145.3mm - more than twice as much as normally expected, the Met Office said.
June saw long, prolonged rainfall and short but exceptionally heavy showers, which ended with storms battering Wales, the Midlands, the North East and Northern Ireland.
A Met Office spokesman said there had been unsettled weather in some parts of the UK for the whole of the past three months, with only the latter half of May seeing a spell of prolonged fine weather.
"Movements in the track of the jet stream, a narrow band of fast flowing westerly winds high in the atmosphere, have contributed to the weather we have seen," the spokesman said.
Wales and Northern Ireland had their wettest June on record, England experienced the second wettest and Scotland the eighth wettest.
Events throughout June were disrupted by the weather - race-goers at Ascot were drenched, the Olympic torch was doused and festival-goers on the Isle of Wight were mired in mud.
*New figures are compared with the 1971-2000 rainfall average, which was 72.6mm