Power cuts, road closures and falling branches threaten widespread mayhem with relentless, lashing rain putting swathes of the UK on flood alert from tomorrow.
The storm will drag icy Polar air across the country through the coming days sending temperatures plummeting and bringing fresh snowfall.
Winds could be strong enough to generate the fourth named storm of the season – Deirdre – although the Met Office and Met Eireann are yet to issue a title.
Powerful gales will lash coastal regions hurling colossal waves over sea defences putting homes and businesses at risk of devastating floods.
Unsettled weather will set in across north-western Britain and Northern Ireland tonight before the whole country comes under fire before the weekend.
Met Office spokesman Grahame Madge said: “A band of rain will move across the Irish sea and into western Britain on Thursday night extending across the UK through the night.
“We are looking at a much bigger pulse of rain coning in on Friday as a separate low-pressure system arrives from the Atlantic.
“This will affect all parts of the UK on Friday and into the weekend, there will be strong winds associated with this and it will remain windy into Saturday.
“Exposed and coastal regions will see the strongest winds with gusts of 60mph while inland gusts could touch 50mph.”
A change in airflow will bring chilly winds in from the north through the weekend triggering hail showers, thunder and further rainfall, he added.
UK weather forecast: A hurricane-strength storm is set to smash Britain unleashing a weekend of hell
He said: “We start to see returning Polar maritime air move across the country behind this system so it will feel much cooler over the weekend compared to the mild conditions of the past week.
“Winds will ease through the start of the weekend but we go into a much more showery and unstable weather regime, some of these showers will be thundery and there could be hail.
“We stay in this pattern through the weekend and the start of next week before high pressure starts to build from the Continent on Tuesday bringing a milder and calmer spell.”
Government forecasters have issued a warning for heavy rain across parts of Scotland and Northern Ireland tonight.
Further more widespread warnings for strong winds and torrential downpours are in place from tomorrow lunchtime until midnight.
The warning region has been increased from earlier in the week to include London and south-east England; south-west England; Scotland; Wales and Northern Ireland, the Met Office said.
Chief forecaster Dan Suri warned strong winds and heavy rain threaten damage to buildings and rush-hour travel chaos.
He said: “A spell of heavy rain and strong winds is expected on Friday.
“A few homes and businesses could be flooded, spray and flooding on roads will make journey times longer.
“Some delays to road, rail, air and ferry transport are expected with delays for high-sided vehicles on exposed routes and bridges.
“There could be some short term loss of power and other services, coastal routes, sea fronts and coastal communities may be affected by spray or large waves.”
The Environment Agency (EA) has put out a raft of flood alerts across southern and south-western Britain ahead of the deluge.
Heavy rain could push rivers to overflow while strong winds threaten to bring huge waves tumbling over coastal walls.
An EA spokesman said: “Local flooding is possible from surface water in parts of the south-west of England and south-west Wales on Thursday.
“Flooding is also probable from surface water and possible from rivers in parts of the south of England and south Wales on Friday and Saturday.
UK weather forecast: Colder air will sweep across the UK
UK weather forecast: Winds could be strong enough to generate Deirdre
“Local coastal or tidal flooding is possible along the south coasts of England and Wales on Friday and Saturday.
“Land, roads and some properties may flood and there may be travel disruption.”
Weather charts show the furious swirling vortex hurtling towards Britain with an expected time of impact around tomorrow lunchtime.
Hurricane-force coastal winds could touch 75mph with the whole of the country in the firing line as the storm sweeps through.
Cold air circulating the churning low-pressure system will flood in from the north sending temperatures plummeting.
The whole country will shiver in single-figure lows through the coming nights with colder weather expected to last into next week. the Met Office said.
Weather models show a risk of snow across the hills of Scotland although some forecasters warn flurries could fall to lower levels.
Exacta Weather forecaster James Madden said: “We are about to see a change back to cooler conditions brining a return of snow to the north with the risk of wintry weather to lower levels.
“This will be accompanies by stormier conditions over the next few days, heavy rainfall will bring a risk of flooding in places and there will be some strong winds.
“With stormier weather likely to continue, this colder incursion will bring an increased risk of gathering snow to higher ground and wintry showers away from the hills.”
WeatherAction’s Piers Corbyn added: “Scotland and northern Britain could turn very cold and there will be a risk of some snowfall across these regions over the next few days.
“There could be some snow, sleet or rain across central regions although the outlook here is mainly dry.”
Daytime temperatures will just nudge double figures over the weekend with the mercury dipping to freezing in the north while hovering below 10C (50F) elsewhere.
AccuWeather forecaster Eric Leister warned winds may be strong enough to push meteorological services to name tomorrow’s storm.
He said: “A powerful storm system will approach the UK on Friday, bringing the risk for damaging winds and further flooding problems.
“This system could potentially become a named windstorm, showers will be wintry across the highest terrain of Wales, Northern England and Scotland on Sunday.
“Peak wind gusts of 50-75 mph are likely throughout southern and western parts of the UK especially in exposed coastal and higher-terrain locations,” added fellow AccuWeather meteorologist Tyler Roys.
“Tree damage, power cuts and coastal flooding are other concerns on Friday.