Strong winds of up to 80mph are forecast in northern parts of England and Wales on Friday, with travel disruption, flooding, power cuts and dangerous conditions near coastal areas likely.
British Airways has cancelled 16 flights scheduled to take off from Heathrow on Friday and delayed others, according to the airline’s website.
The cancellations include international flights to Italy, Switzerland and the US as well as domestic journeys to Scotland and Northern Ireland.
The flights between Belfast and London impacted are the 1.30pm arrival into Belfast City Airport and the 2.15pm departure leaving the Northern Irish airport for Heathrow.
A spokesperson for British Airways said: “Due to restrictions imposed by air traffic control as a result of adverse weather across the UK, we’ve made some minor adjustments to our schedule.
“We’ve apologised to our customers for the disruption to their travel plans and to help get them to their destinations as quickly as possible.”
Two flights from Leeds Bradford Airport were cancelled on Friday while three morning arrivals were diverted to Liverpool, according to the airport’s website.
The Met Office has issued a yellow weather warning for rain spanning much of South East England from 6am to 1pm on Saturday.
The forecaster warned people in the affected area, which stretches from the Isle of Wight up to Ipswich in Suffolk and includes London, should expect “spells of rain, heavy at times, likely to cause some travel disruption and perhaps flooding in a few places”.
A separate wind warning was also in place across northern England and north Wales until 11am on Friday, with the storm widely expected to bring gusts of 50-60mph in the region.
The Met Office posted on social media site X on Friday morning: “Winds are now strengthening in many areas with the strongest winds occurring during the next few hours across northern England and north Wales.
“Damaging gusts are possible in places so ensure you stay #WeatherAware.”
The RAC estimates 19.2 million leisure trips by car will be made over the weekend, with 3.2 million on Friday alone.
This is highest since the motoring services company began recording data for the summer bank holiday in 2015.
RAC Breakdown spokeswoman Alice Simpson said the adverse weather and large volume of expected trips represents “a perfect storm” for drivers.
She said: “Anyone driving in areas impacted by Storm Lilian should try to avoid exposed coasts and higher routes where there’s a greater chance of fallen branches and trees. It’s vital to lower your speeds and leave plenty of extra stopping distance to allow yourself time to react quickly.
“Drivers should keep a firm grip on the steering wheel and take extra care when passing high-sided vehicles which can cause an unnerving buffeting effect when you’re suddenly hit by the wind on the other side.”
Met Office forecaster Greg Dewhurst said: “The strongest winds are likely to start forming through the early hours initially across parts of north Wales into the Liverpool, Blackpool area, and then crossing over the Pennines and into the east and north-east England – Yorkshire, up to Northumberland – before then clearing out into the North Sea.
“It’s really quite quick.”
The high winds led to two stages at Leeds Festival being closed for the day.
On X, Reading and Leeds Festivals announced the BBC Radio 1 Stage and Aux Stage would be “lost” at the West Yorkshire site, but it “remains hopeful that everything else will continue as planned”.
The event had earlier issued an “urgent weather report” on social media, warning attendees to stay in their tents if they are already on site and urging others on their way to delay their arrival.
Acts including indie singer Beabadoobee and US star Ashnikko were due to play the BBC Radio 1 Stage at Leeds on Friday evening, while podcasts Antics With Ash and The Useless Hotline were billed for the Aux Stage.
Blink 182 are headlining Reading Festival on Friday night while acts including Gerry Cinnamon, Two Door Cinema Club and The Prodigy will also take to the stage.
A Network Rail spokeswoman said: “We are closely monitoring the potential impact that the storm might have on the rail network.
“We have teams on hand to put in appropriate measures, if necessary, to ensure that we can continue to run trains safely and as reliably as possible.”
Lillian’s influence should “wane” by Friday afternoon as it reduces in intensity and is pushed off into the North Sea, with scattered showers for most of the rest of the day, forecasters said.
After the possibility of some heavy showers early on Saturday, settled conditions are likely to develop across southern and eastern England and Wales, with sunny spells and dry conditions mixed with the odd chance of scattered showers.
But the North and North West could continue to see “a fairly unsettled weekend”, with persistent rain in places, particularly parts of western Scotland and Northern Ireland.
Temperatures will reach highs of 21C on Saturday and Sunday and 23C on Monday in the South East, slightly below average for the time of year.
Lilian is the 12th named storm of the season – the furthest the Met Office has got through the list since it was introduced – and the first since April.
Storms are named when they have the potential to cause disruption or damage which could result in an amber or red warning, the Met Office said.