A powerful weather system developing over the Atlantic could see Britain battered tonight with some of the worst weather conditions since the Great Storm of 1987, forecasters are predicting.
The weather system, dubbed the St Jude's Day Storm - named after the patron saint of depression and lost causes, whose feast day is Monday - is expected to reach the south coast of England on Sunday night and into Monday, bringing exceptionally strong winds.
It could develop winds hitting 12 on the Beaufort Scale - the strength of a hurricane.
Eight flights between Ireland and London Heathrow have been cancelled.
Aer Lingus took the step on Sunday afternoon as England and Wales braced itself for severe weather. Services between Dublin, Cork, Belfast and Heathrow are affected.
The Prime Minister David Cameron tweeted to say he had chaired a discussion on plans to protect people from the storm.
Winds of more than 80mph could leave a trail of destruction across a large swathe of the UK, bringing down trees and causing widespread structural damage, leading to power cuts and transport chaos tomorrow morning.
Surface water floods could strike much of England as the Met Office predicts 20-40mm of rain could fall within six to nine hours overnight.
Insurance companies have advised households to take steps to protect themselves and their property.
People should also establish evacuation plans, place valuable items upstairs to limit flood damage and ensure gutters are clear so water can drain away.
With gusts of up to 90mph and up to 40mm of rain forecast the RAC has warned motorists against all but essential travel in torrential rain and floods.
There had been some doubt over whether the storm would even hit the UK. But yesterday the Met Office confirmed it is expected to sweep through the south of the country.
The public has also been warned to expect the possibility of power cuts, trees blocking roads and transport disruption. Anticipating disruption, the Metropolitan Police urged people to avoid calling 999 during the storm unless there is a real emergency.
A spokesman said: “Calling 999 when it is not an emergency can reduce our effectiveness at dealing with genuine emergencies.”
Met Office spokesman Dan Williams said on Friday that forecasters had extended their amber warning for strong winds further north. London, East Anglia, Bristol and as far north as the Midlands are all now expected to be hit by heavy winds and rain.
Forecasters say it is now looking more likely than before that the storm - with wind speeds of 80mph or more - will cross the southern half of Britain, rather than passing south of the country - and a larger area than previously thought could be affected.
Met Office spokesman Dan Williams explained why the storm was potentially so significant: "These storms usually develop much further out in the Atlantic, so when they come over the UK they are in the declining phase and decrease in strength.
"What we're seeing with this one is that it developed very rapidly much closer to the UK."
"There is a system of low pressure developing across the Atlantic but it doesn't start to deepen until it's quite close to the UK."
"It then deepens very rapidly. It is still maintaining or gaining strength as it moves across the country."
"That's why this has the potential to be quite a significant storm. Because it will be at its most vigorous stage of development while it goes over the UK."
"The most similar one in terms of track and strength would be the Burns Day storm of 25th January 1990."
Frank Saunders, Chief Forecaster at the Met Office, said: "We are confident that a severe storm will affect Britain on Sunday night and Monday. We are now looking at refining the details about which areas will see the strongest winds and the heaviest rain.
"This is a developing situation and we'd advise people to stay up to date with our forecasts and warnings over the weekend, and be prepared to change their plans if necessary. We'll continue to work closely with authorities and emergency services to ensure they are aware of the expected conditions."
Met Office senior forecaster Helen Chivers warned that winds could get up to 90mph and said the storm could be exceptional: "This is not a storm you see every winter."
"The storm of 1987 is one, and the Burns day storm in January 1990 is another."
"It is important to realise the track of this low is at the moment not certain. In this type of situation it is really, really important that people keep up to date with the most up to date warnings."
Forecasters said this storm was unusual as it has developed much closer to UK and could potentially be tracking across the country while still in its most powerful phase. A strong jet stream and warm air close to the UK are both contributing to the development and strength of the storm, the Met Office said.
Public in the affected area "should be prepared for the risk of falling trees as well as damage to buildings and other structures" caused by strong winds, forecasters said.
The Environment Agency has teams working to minimise river flood risk, clearing debris from streams and unblocking culverts, and are closely monitoring water levels so they are ready to issue flood warnings if necessary.
A spokesman said: "We are supporting local authorities who will respond to any reports of surface water flooding.
"Seafronts, quaysides and jetties should be avoided due to the risk of overtopping by waves and wind-blown shingle."
The Great Storm of 1987
Last week saw the 26th anniversary of one of the worst storms in British history.
The Great Storm, as it is often called, hit Britain in the early hours of 16 October 1987. The storm was the worst to hit Britain in over three hundred years and claimed 18 lives, caused £1.5bn worth of damage and brought down an estimated 15 million trees.
At one point the winds reached speeds of 120mph. The National Grid sustained heavy damage leaving thousands without power.
At the time forecasters were criticised for failing to predict the storm. In particular BBC meteorologist Michael Fish drew opprobrium after saying in his broadcast: "Earlier on today, apparently, a woman rang the BBC and said she heard there was a hurricane on the way; well, if you're watching, don't worry, there isn't, but having said that, actually, the weather will become very windy, but most of the strong winds, incidentally, will be down over Spain and across into France."