Heavy rain is set to hit swollen rivers in Cumbria, where some regions have been hit by flooding three times within a month.
Up to six inches of rain is expected in the county, which has already suffered the wettest December since records began in 1910.
Ministers will hold a Christmas Day conference call to discuss the Government’s preparations, with Armed Forces personnel on standby for more flooding today as the North braces for further wild weather.
Major Nick Higgins, from 2nd Battalion the Duke of Lancaster’s Regiment, told Sky News it was “business as usual” over the festive season for the many soldiers helping prepare flood defences in Appleby.
Some 700 Environment Agency staff have also been deployed as flood warnings were issued in the North and Scotland for late on Christmas Day and Boxing Day.
The agency has eight flood warnings still in place, meaning flooding is expected, with a further 82 flood alerts – meaning flooding is possible.
Throughout Christmas Day the rain will spread across Wales and northern England. It will reach parts of southern Scotland early on Boxing Day.
Many towns and villages across Cumbria are still cleaning up from Storm Desmond earlier this month, which caused damage to hundreds of homes and businesses.
Around 40 roads and bridges remain damaged and closed, and hundreds of homes have been left uninhabitable.
Early on Christmas Eve 2,000 customers were without power in Ireland as Storm Eva crossed the country, with the worst affected areas including County Cork and County Wicklow. Electricity was restored for most by Thursday evening.
Storm Eva has now passed over the north of the UK, but the Army is bolstering flood defences in Cumbria ahead of the further rainfall.
Cumbria Police are urging motorists on the road over Christmas to “adapt their driving style” and be aware of changing conditions.
“Please do not in any circumstance ignore road closure signs and continue on your journey,” said Chief Inspector Matt Kennerley.
“Driving through flood water is extremely dangerous as you cannot determine the depth.”