More than a month's rain is expected to fall in just two days across parts of the UK.
A severe weather warning has been issued by the Met Office , with fears of flooding and disruption on Friday and Saturday.
Central and northern England are expected to be worst affected, with an amber alert in place for north east England.
Up to 3.9 inches (100mm) of rain could fall in 36 hours during the downpours. The average UK rainfall for July is 2.8 inches (69.9mm).
Sky News weather presenter Isobel Lang said: "Our weather is showing no signs of settling down despite already enduring a record-breaking wet April and June.
"After today's showers and thunderstorms across eastern and northern Britain, Friday will see prolonged and heavy rainfall spreading up across East Anglia, the Midlands, Wales and into southern Ireland.
"Atrocious driving conditions are expected along with some flooding.
"Saturday will bring yet more wet weather, this time mainly across north east England and southern and eastern Scotland again bringing a flood risk.
"Showers on Sunday could be heavy across southern Britain."
People living in the affected areas have been warned to be prepared for flooding.
An Environment Agency spokesman said: "Heavy rain on Friday and Saturday may lead to significant flooding of properties across parts of northern England.
"We urge people to remain vigilant and prepared for flooding by checking the Environment Agency website and signing up for localised river flood warnings.
"We have mobilised teams across the country to check flood defences, clear any river blockages and closely monitor river levels to help reduce the risk flooding."
The wet weather has already caused delays to some of this year's big summer sporting fixtures, including Wimbledon and England Test matches.
Last month was the wettest June since records began, with double the average rain falling during the month.
The exceptional amount of rain caused floods in Wales and parts of England.
It was the second month this year to see record-breaking amounts of rain, with April also the wettest, according to records dating back more than a century to 1910.
So far this summer there has only been one spell of prolonged fine weather during the second half of May.
The wet weather is set to continue for two weeks. Sunshine and warmer weather could arrive later this month, in time for the Olympic Games in London.