Urgent flood warnings have been issued amid fears of flooding in the north - with locals warned to take "immediate action".
The Environment Agency has identified 24 places where flooding is expected, with nearly one month's rainfall to lash the country.
Weather warnings remain in place for severe rainfall, expected to move from south to north across swathes of the UK.
Forecasters say the downpours will be thundery at times and led to flooding.
In each of the places where a warning is in place, "immediate action" is required, the Met Office says.
In some places, including Greater Manchester, rain is not expected to stop until 9am - with more thunderstorms to come on Tuesday and Wednesday.
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On top of this, 24 flood alerts are in place, meaning people should be prepared for flooding.
The Environment Agency's flood warnings are:
- Grace Dieu Brook at Whitwick and Thringstone
Midgelden Brook at Bacup Road, Gauxholme
Hey Brook at Rochdale
- Poynton Brook at Wigwam wood and parts of Armcon Business Park
- River Calder at Burley Town Centre
- River Calder at Central Todmorden
- River Calder at Todmorden from the Cricket Ground to the Railway Bridge
- River Calder at Todmorden - Harley Wood
- River Calder at Todmorden - Millwood
- River Calder at Todmorden - Patmos Burnley Road
- River Lostock, Shaw Brook and Bannister Brook at Leyland
- River Mersey at Cheadle Wood and Ford Lane
- River Mersey at Fletcher Moss and Withington Golf Course
- River Roch in Rochdale
- River Spen and Canker Dyke at Ravensthorpe
- River Spen and Lands Beck from Knowler Hill to Wormald Street, Liversedge
- River Spen from Hunsworth to Brooklyn Road, Cleckheaton
- River Spen from Wormold Street to Smithies Lane
River Spodden at Whitworth
Timperley Brook at Altrincham
- Walsden Water at Walsden
- Whinney Brook and Dovers Brook at Maghull, around Hall Lane, Damfield Lane and Foxhouse Lane
Whinney Brook and Dovers Brook at Maghull, between Sefton Lane and the Waste Transfer Station
A further 19 waterways are subject to a less severe warning to "be prepared" for flooding.
In many areas, between 41mm and 50mm of rain falls on average every July.
But 40mm is expected to lash across the country in just a few hours tomorrow.
Earlier on Sunday the M60 and the A555 were closed because of flooding, the Manchester Evening News reports.
The M60 reopened later, but Greater Manchester Police is urging people to stay alert.
The Met Office's weather warning states: "Thunderstorms and outbreaks of heavy rain will arrive across the far southwest early on Tuesday, then spreading further northeast across England and Wales and increasing in frequency during the day.
"In a few places there is the potential for 30mm of rain to fall in an hour or two and 40mm to fall in three hours. Many parts of the warning area will miss the heaviest rainfall."
And forecasters suggested summer is over - with no return of last week's scorching heatwave.
Helen Roberts, forecaster for the Met Office, said: "The warning is in place for most of Tuesday and covers the whole of Wales. There will be an improvement on Wednesday. On Thursday and Friday there will be a few showers around, but at the moment it is looking largely fair for next weekend.
"There is not another heatwave in the forecast at the moment."
A statement on the Met Office website said: "An area of heavy rain is expected to become slow moving across parts of northern England and perhaps southern Scotland on Saturday and Sunday.
"Rainfall accumulations of 40-60mm are likely, with perhaps as much as 80-120mm over high ground of the Pennines and North York Moors."
