Heavy rain and gales of more than 100mph have returned to Britain overnight - just days after the last storm caused Christmas misery for tens of thousands of people.
The Met Office has issued yellow and amber weather warnings, indicating "severe or hazardous weather" with potential to "cause danger to life or widespread disruption" and urged many people to prepare for flooding.
The storm will spread east across the whole of the UK throughout the morning, with the worst-affected areas expected to be northern England and northern parts of Wales, the Met Office said.
Police and fire services up and down the country have already reported road closures because of uprooted trees.
The Met Office recorded a gust of wind in Aberdaron, in west Wales, of 109mph early this morning - with general wind speeds of between 60mph and 80mph expected in the UK.
Dublin Airport tweeted that it has had to divert six planes because of strong winds.
"We had six diversions due to high winds gusting across both runways," it said. "Winds abated slightly and two flights landed recently."
The Environment Agency (EA) is warning of more "significant disruption" across southern England, saying: "It is possible that heavy rain may worsen the current flooding situation in some areas with rivers responding quickly to rain falling on already saturated ground."
The rain will exacerbate ongoing river flooding across the Somerset Levels, River Severn, River Thames and River Ouse in Cambridgeshire and rivers across Essex, as well as along the River Medway and the Kentish Stour around Ashford and Canterbury.
There are 52 flood warnings and 157 flood alerts in place, but the EA said the number of alerts may increase as rivers respond to the further band of rainfall.
It comes after more than 43,000 people were left without power following Monday night's storm and around 1,200 properties were flooded in England.
Lara Gunn, a forecaster for MeteoGroup, said the latest weather system is pushing in from the west overnight resulting in widespread rain of up to an inch and forceful winds of up to 80mph along the coast and up to 60mph inland.
"Almost everywhere will be affected by the widespread gales and rain but it will clear throughout the morning," she said.
The storm is expected to cause fresh travel problems for airlines, train operators and bus companies as well as for drivers returning to work or home following the Christmas break.
Network Rail advises that routes will need to be checked at first light and tracks will need to be cleared of any fallen trees and any damage will need repaired before train services can start.
Southeastern said it is unlikely it will be able to run any metro or mainline train services until at least midday, while Network Rail added that services in Kent and Anglia will be delayed.
Robin Gisby, managing director of network operations at Network Rail, said: "Passengers have had a tough week of travelling and unfortunately that is likely to continue for at least another day.
"Thousands of railway workers have worked tirelessly over the holiday period to try and repair the significant damage caused by Monday's storm and will be called on again over the next 24 hours.
"As ever, safety comes first, as we ensure routes are safe for passengers services leading to a delayed start-up in some regions."
In a weather warning, Gatwick Airport said it had "additional teams of engineers, electrical staff and volunteers at the airport to minimise the risk of disruption from potential further flooding".
Flights at Gatwick were affected when chaos ensued on Christmas Eve after a power outage at the North Terminal, and the Civil Aviation Authority (CAA) said it expected the West Sussex airport's bosses to examine exactly what caused the mayhem before deciding what further action to take.
A spokeswoman for the airport said it was currently operating on schedule, and said wind speeds of 45 knots is expected overnight and this morning.
"We are telling passengers to check with their airline in advance," she said.
She described this week's weather as "unprecedented", and said it was the combination of gales and heavy rain that caused the problems.
On a visit to meet EA staff in Byfleet, environment minister George Eustice said: "Having your home or business flooded at any time of year is an awful experience but especially so at Christmas and I would like to extend my sympathy to everyone who's been affected over the past couple of days.
"The emergency services, Environment Agency and power providers are working around the clock to ensure the floodwater is cleared and power returned to people's homes and businesses.
"With the potential for more flooding tonight, I urge everyone to follow the safety advice from the police and emergency services and be as prepared as possible by signing up to environment agency flood alerts."
Police have warned drivers to drive with "extreme caution" as trees are blown into the roads by ferocious winds.
Cheshire Police tweeted their particular concern for drivers of high-sided vehicles, which are at risk of being blown over by the gale-force winds.
It also reported "awful driving conditions" and a number of roads blocked by fallen trees.
"Many trees down due to strong winds. We would ask all drivers to exercise extreme caution whilst driving tonight," the force tweeted.
"Drivers of high sided vehicles should use extreme care when driving tonight. Particularly #Thelwall viaduct and the #Runcorn #Widnes bridge."