Heavy snow storms, which have stranded drivers for hours on motorways in the north of England, will make way for rain - sparking fears of flooding.
The M6 was blocked in both directions between junctions 25 and 27 in Lancashire when a sudden burst of more than a foot of snow brought drivers to a standstill around 8.30pm, said the Highways Agency.
Many became stuck along the stretch of motorway between Wigan and Standish after struggling to make it up inclines in the treacherous conditions, while a number of accidents including jack-knifed lorries also blocked lanes.
The M6, as well as the M56 and M58 which were also blocked, are now all moving again but remain heavily congested with long tailbacks, said Lancashire Police.
Chief Inspector Mike Adamson said: "We realised at about 11pm last night that this was going to be a major incident. Some of the drivers and passengers have been stuck for hours - it has been a very difficult night for them. We have set up a command centre at Charnock Services, where officers have collected hot drinks and taken them to those who are stuck."
Some of the stranded drivers passed the time with snowball fights and building snowmen, while others abandoned their cars completely. One man had to be taken to hospital by Lancashire Police after becoming ill in his car while it was stuck.
Lancashire Police also worked with Lancashire Mountain Rescue teams, the Highways Agency and neighbouring force Greater Manchester Police to clear roads and provide welfare assistance to those who were stranded. The Highway Agency worked throughout the night to clear the routes with snow ploughs.
A spokesman for the agency urged those who had abandoned their cars to return to them as soon as possible.
He said: "The snowfall was very sudden and very heavy - over a foot in some places - causing cars to become stranded. But we have managed to get through the traffic and clear most routes to get people moving again.
"We are urging those who have abandoned their cars to collect, all we can do is move them to the side for now but it makes it difficult to clear routes. With the rain falling and ice melting onto very cold road surfaces, we are now warning drivers of the danger of ice."