The UK's cold snap has given way to soaring temperatures with warnings of heavy rain and some flooding, as people prepare for the Christmas getaway.
Yellow alerts for rain are in place until 06:00 GMT on Tuesday in southern England and South Wales.
After freezing conditions last week, forecasters said Monday could bring highs of up to 15C in some parts.
The Met Office said flooding could hit homes and businesses, as well as causing disruption to road travel.
It added that bus and train journeys could also be impacted as downpours hit areas including Brighton, Plymouth and Portsmouth in the south of England, and Newport in Wales on Monday.
There are nine flood warnings in place and 49 flood alerts issued across the country.
More people may also choose to travel on the roads as thousands of members of the Rail, Maritime and Transport union (RMT) strike from 18:00 on Christmas Eve.
The RAC predicts 7.9 million journeys will be made over the two days immediately before Christmas Day, with the worst congestion expected between 10:00 and 19:00 on Friday, and between 12:00 and 13:00 on Saturday.
RAC spokesman Rod Dennis said: "If possible, drivers should try to make their trips on a quieter day earlier this week if they possibly can."
The AA also issued an "amber traffic warning" for Friday and Saturday, as they urged motorists to carry out car checks including levels of fuel, oil, coolant and screen wash, along with ensuring tyres are correctly inflated.
Peter Jenkins from Water UK urged people to check that their water pipes were well insulated, following the freezing weather.
"The last thing we want is for people to experience further disruption as temperatures rise… putting many homes at risk of burst pipes due to freeze-thaw."
Scottish Water said it had seen a rise of 150% in burst pipes in recent days as sub zero temperatures tuned to rapid thaw, with an extra 100 million litres of water a day passing through them.
Welsh Water also said there had been a number of leaks due to the "rapid thaw" – with one pub facing a huge clean up after pipes burst and water poured in from the ceiling.
Warnings for snow and ice were previously in place for much of the country up to Sunday – including an amber alert for ice in parts of northern England.
The severe weather caused widespread disruption – bringing temperatures as low as -17.3C in Scotland on Tuesday – the coldest temperature since February 2021.
But BBC Weather said on Sunday that the bitterly cold, frosty weather was turning "to something much milder, wetter and windier".
Presenter Jennifer Bartram said: "The big swing in temperatures will be noticeable on Monday, and though it is unusual to see such a dramatic change, it's not unheard of.
"The change is all linked to where our air is coming from – we're replacing bitterly cold Arctic air with something much milder from the Atlantic."
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