Thousands of people have been forced to leave their homes amid severe flooding across England and Wales that is now believed to have claimed four lives.
Hundreds of families in Lincolnshire, South Yorkshire, Nottinghamshire and Shropshire have been moved to safety.
In Worcestershire police searching for a missing motorist have found a body.
On Monday, a man and a teenage boy were swept to their deaths in Sheffield and another man died after becoming trapped in a storm drain in Hull.
About 900 people are using emergency shelters in Sheffield, and about 700 have left villages near Rotherham, South Yorkshire, amid fears the nearby Ulley dam could collapse.
Up to 21 severe flood warnings are still in place, but forecasters say the worst of the weather has passed.
Other key developments:
Police have closed the M1 northbound between junctions 32 to 34, and southbound between junctions 34 and 32, because of the risk the Ulley dam poses
Rail companies including Virgin Trains, Midland Mainline and Arriva Trains Wales have announced cancellations and amendments to their services
London Fire Brigade have sent two "high volume pumps" to West Yorkshire to help with the flooding problems
About 20 houses have been evacuated in Ludlow, Shropshire, after the main bridge into the town collapsed, bursting a gas main. A 40-foot section of a main road leading into Ludlow was washed away by the River Corve
A block of 120 flats in Lincoln was evacuated by dinghy because the River Witham has begun seeping through its banks at Stamp End in the city
People have also been evacuated from Worksop in Nottinghamshire, Lincoln, Louth and Wainfleet in Lincolnshire and Chesterfield in Derbyshire
Environment Secretary David Miliband told the House of Commons there were no reports of flood defences failing but said the government would "consider lessons learned".
Prime Minister Tony Blair expressed his sympathy to the families of the dead and those displaced by what he described as an "extraordinary and very serious event".
"The immediate thing is to make sure we get the right co-ordination with the emergency services... and that we try to make sure we prevent any further loss of life," he said.
The Environment Agency labelled current weather conditions "phenomenal".
The agency's flood expert, Phil Rothwell, said: "We've had a sixth of the annual rainfall in 12 hours.
"Climate change experts tell us that this is the sort of thing we need to expect for the future."
Of the 21 severe flood warnings in place, 13 are in north-east England, seven in the east of the country and one in the Midlands.
The Met Office, which forecasts the weather and works closely with the Environment Agency in dealing with floods, had issued an early warning last Friday.
It had correctly predicted that 50-100mm of rain would fall in the 24 hours from 2200 BST on Sunday, with the worst-affected areas being Yorkshire and Lincolnshire.
Meanwhile, finance chiefs are warning that the floods will cost small businesses millions, and insurers are expecting tens of millions in claims from homeowners.
The government has offered emergency aid to the worst affected areas to help with the cost of the clear-up.
South and East Yorkshire saw some of the heaviest flooding, with thousands of homes left without power and three people dying.
A 68-year-old man was killed after being swept away as he tried to cross a road in central Sheffield.
In a separate incident in the city a 14-year-old boy, named as Ryan Joe Parry, was killed after falling into the River Sheaf at Millhouses.
And 28-year-old Mike Barnett died after becoming trapped in a storm drain in Hull.
He had been trying to help his grandfather clear the flooded drain in the Hessle area.
Hundreds of people have left their homes in the villages of Whiston, Canklow, and Catcliffe and Treeton, amid fears the Ulley dam could collapse.
Jamie Courtney, South Yorkshire Fire Service's head of service delivery, said: "We have a real possibility of failure of the Ulley reservoir wall, the consequences of which would be widespread damage and flooding.
"This is a precautionary measure for the public's safety and we would ask people to co-operate fully."
Police have also found the body of a man after a search for a motorist feared to have been washed away in his car by rising water at Bow Brook, Pershore, Worcestershire.
And in north Wales, fire crews have rescued a man who had been marooned on a small piece of land in the middle of the River Dee in Llangollen since Sunday.
BBC weather forecaster Philip Avery said the worst of the weather had passed.
"Long term the outlook is pretty unsettled going into the weekend, but nothing of the order of what we have had," he said.
FLOODING IN ENGLAND
Man dies after being trapped in a drain
Fire crews receive 1,500 emergency calls in a 12-hour period
Teenage boy and a 68-year-old man swept to their deaths by floodwater
900 people evacuated to emergency shelters
Officials estimate "significant damage" to the city
Severe disruption to road and rail transport
70 houses in Halton area evacuated
5 schools closed
Bridge collapses severing a gas main
100 people evacuated
Nine-year old boy rescued from swollen river and 60 houses evacuated in Louth
Block of 120 flats evacuated in Lincoln
5 schools remain closed due to flooding
88 people rescued by fire crews, all uninjured
2ft of floodwater
Closed between junctions 32 and 36
Ulley reservoir, nr. Rotherham:
Nearby villages evacuated over fears dam may burst
The Environment Agency has advised people worried about flooding to call its Flood Line on 08459 881 188.