Thunderstorm warnings have been issued across England and Wales by the Met Office as heavy rain and lightning are expected to hit from Wednesday.
While many areas will see little rainfall, forecasters warn there is a risk flooding and lightning strikes could cause power cuts and delays to train and bus services in some parts of the country, particularly late in the afternoon.
It could also cause difficult driving conditions and road closures.
The thunderstorm warning is in place from 11am until 9pm on Wednesday, where torrential downpours could see 30-50mm of rainfall in less than three hours in some areas.
Recommended UK weather forecast: Temperatures to soar next week as ‘heatwave’ hits England and Wales September heatwave: When are UK temperatures set to soar? Why has Scotland had the best of the weather this summer?
Another warning for stormy weather and heavy showers has also been issued for the Midlands, north and southwest from 11am to 8pm on Thursday, with up to 40mm rainfall predicted.
There is also a small chance that properties could be flooded quickly and rural communities could become cut off by flooded roads.
The unsettled weather will mark an end to a hot start to September, which saw temperatures reach nearly 30C in central and eastern England on Tuesday.
Meanwhile, forecasters have said some areas are edging close to recording an official heatwave this week as pupils head back to school.
On Monday, the maximum UK temperature was logged at 28.9C in Larkhill, Wiltshire, closely followed by the 28.8C recorded at Santon Downham, Suffolk, and 28.7C at Middle Wallop in Hampshire.
UK news in pictures Show all 50
1/50UK news in pictures
UK news in pictures Mixing it up: Painting it up press view in London A gallery employee poses for photographers next to a painting entitled “Prairie” by British artist, Louise Giovanelli during the exhibition 'Mixing it up: Painting it up' at the Hayward Gallery in London
EPA
UK news in pictures 6 September 2021 Traders in the Ring at the London Metal Exchange, in the City of London, after open-outcry trading returned for the first time since March 2020, when the Ring was temporarily closed due to the pandemic
PA
UK news in pictures 5 September 2021 People enjoy the warm weather on Sandbanks beach, Poole
PA
UK news in pictures 4 September 2021 Demonstrators from Animal Rebellion and Nature Rebellion protest in Trafalgar Square in London.
PA
UK news in pictures 3 September 2021 South Africa's Ntando Mahlangu (centre) wins the Men's 200 metres T61 Final ahead of second placed Great Britain's Richard Whitehead at the Tokyo 2020 Paralympic Games
PA
UK news in pictures 2 September 2021 A young common seal on the beach at Horsey Gap in Norfolk, as hundreds of pregnant grey seals come ashore ready for the start of the pupping season.
PA
UK news in pictures 1 September 2021 Goldfinches fighting over food in a garden in Strensham, Worcestershire
PA
UK news in pictures 31 August 2021 Gold Medallist Sarah Storey of Britain celebrates on the podium
Reuters
UK news in pictures 30 August 2021 Extinction Rebellion protesters hold a a tea party on Tower Bridge in London
EPA
UK news in pictures 29 August 2021 A police office tussles with a demonstrator on Cromwell Road outside the Natural History Museum during a protest by members of Extinction Rebellion in London
PA
UK news in pictures 28 August 2021 Members of the British armed forces 16 Air Assault Brigade walk to the air terminal after disembarking a Royal Airforce Voyager aircraft at Brize Norton, Oxfordshire
POOL/AFP/Getty
UK news in pictures 27 August 2021 Fabio Quartararo crashes during a MotoGP practice session at the British Grand Prix, Silverstone Circuit
Action Images via Reuters
UK news in pictures 26 August 2021 An Extinction Rebellion activist holds a placard in a fountain surrounded by police officers, during a protest next to Buckingham Palace in London
Reuters
UK news in pictures 25 August 2021 Gold Medallist Great Britain’s cyclist, Sarah Storey, celebrates after winning the Women’s C5 3000m Individual Pursuit Final at the Tokyo 2020 Paralympic Games. It was her 15th Paralympic gold
Reuters
UK news in pictures 24 August 2021 A demonstrator dressed as bee during a protest by members of Extinction Rebellion on Whitehall, in central London
PA
UK news in pictures 23 August 2021 Former interpreters for the British forces in Afghanistan demonstrate outside the Home Office in central London
AFP/Getty
UK news in pictures 22 August 2021 Police officers form a line in front of the entrance to the Guildhall, London, where protesters have climbed onto a ledge above the entrance during an Extinction Rebellion stage a protest
PA
UK news in pictures 21 August 2021 People take part in a demonstration in solidarity with people of Afghanistan, in London
Reuters
UK news in pictures 20 August 2021 People zip wire across the sea from Bournemouth pier towards the beach.
PA
UK news in pictures 19 August 2021 Supporters of Geronimo the alpaca gather outside Shepherds Close Farm in Wooton Under Edge, Gloucestershire
PA
UK news in pictures 18 August 2021 Former Afghan interpreters and veterans hold a demonstration outside Downing Street, calling for support and protection for Afghan interpreters and their families
PA
UK news in pictures 17 August 2021 Military personnel board the RAF Airbus A400M at RAF Brize Norton in Oxfordshire, where evacuation flights from Afghanistan have been landing
Reuters
UK news in pictures 16 August 2021 Labour leader Sir Keir Starmer takes part in a minute's silence at Wolverhampton police station for the victims of the Plymouth mass shooting last week
PA
UK news in pictures 15 August 2021 2Storm, a ten-metre tall puppet of a mythical goddess of the sea created by Edinburgh-based visual theatre company Vision Mechanics, makes its way alongside the seafront at North Berwick, East Lothian, during a performance at the Fringe By The Sea festival
PA
UK news in pictures 14 August 2021 A woman and two young girls look at floral tributes in Plymouth where six people, including the offender, died of gunshot wounds in a firearms incident
PA
UK news in pictures 13 August 2021 Forensic officers in the Keyham area of Plymouth where six people, including the shooter, died of gunshot wounds in a firearms incident on Thursday evening
PA
UK news in pictures 12 August 2021 Children ride horses in the River Eden in Appleby, Cumbria, during the annual gathering of travellers for the Appleby Horse Fair
PA
UK news in pictures 11 August 2021 Stella Moris (left) reacts after talking to the media outside the High Court in London, following the first hearing in the Julian Assange extradition appeal, n London, following the first hearing in the Julian Assange extradition appeal. The US government has won the latest round in its High Court bid to appeal against the decision not to extradite Julian Assange on espionage charges
PA
UK news in pictures 10 August 2021 Students react after they receive their A-Level results at the Ark Academy, in London
Reuters
UK news in pictures 9 August 2021 The final athletes from Great Britain arrive home including Jason Kenny, Laura Kenny and Katie Archibald (front left-right) at Heathrow Airport, London following the Tokyo 2020 Olympic Games
PA
UK news in pictures 8 August 2021 Great Britain's Laura Kenny during the closing ceremony of the Tokyo 2020 Olympic Games at the Olympic stadium in Japan
PA
UK news in pictures 7 August 2021 People from the Glasgow Southside community take part in the Govanhill Carnival, an anti-racist celebration of pride, unity and the contributions immigrants have made to the community in Govanhill, at Queen's Park, Glasgow
PA
UK news in pictures 6 August 2021 Chijindu Ujah of Britain, Zharnel Hughes of Britain, Richard Kilty of Britain and Nethaneel Mitchell-Blake of Britain celebrate winning silver as they pose with Asha Philip of Britain, Imani Lansiquot of Britain, Dina Asher-Smith of Britain and Daryll Neita of Britain after they won bronze in the women's 4 x 100m relay during Olympic Games Day 14
Getty
UK news in pictures 5 August 2021 A protester places flowers on a photograph of an executed man during a demonstration organised by supporters of the National Council of Resistance of Iran (NCRI) to protest against the inauguration of Iran's new president Ebrahim Raisi in central London
AFP via Getty
UK news in pictures 4 August 2021 England's Joe Root looks on as India's KL Rahul doesn't make it to a catch during day one of Cinch First Test match at Trent Bridge, Nottingham
PA
UK news in pictures 3 August 2021 Great Britain's Laura Kenny and Jason Kenny with their silver medals for the Women's Team Pursuit and Men’s Team Sprint during the Track Cycling at the Izu Velodrome on the eleventh day of the Tokyo 2020 Olympic Games in Japan
PA
UK news in pictures 2 August 2021 Great Britain’s Charlotte Worthington competes during the Women’s BMX Freestyle Final at the Tokyo Olympics
PA
UK news in pictures 1 August 2021
EPA
UK news in pictures 31 July 2021 James Guy, Adam Peaty and Kathleen Dawson celebrate winning the gold medal in the mixed 4x100m medley relay final at the Tokyo Olympics
AP
UK news in pictures 30 July 2021 Great Britain's Bethany Shriever and Kye Whyte celebrate their Gold and Silver medals respectively for the Cycling BMX Racing at the Ariake Urban Sports Park on the seventh day of the Tokyo 2020 Olympic Games in Japan
PA
UK news in pictures 29 July 2021 Team GB's Mallory Franklin during the Women’s Canoe Slalom Final on day six of the Tokyo Olympic Games. She went on to win the silver medal
Getty
UK news in pictures 28 July 2021 Canoers on Llyn Padarn lake in Snowdonia, Gwynedd. It was announced that the north-west Wales slate landscape has been granted UNESCO World Heritage Status
PA
UK news in pictures 27 July 2021 A view of one of two areas now being used at a warehouse facility in Dover, Kent, for boats used by people thought to be migrants.
PA
UK news in pictures 26 July 2021 A woman is helped by Border Force officers as a group of people thought to be migrants are brought in to Dover, Kent, onboard a Border Force vessel, following a small boat incident in the Channel
PA
UK news in pictures 25 July 2021 Vehicles drive through deep water on a flooded road in Nine Elms, London
AFP/Getty
UK news in pictures 24 July 2021 Utilities workers inspect a 15x20ft sinkhole on Green Lane, Liverpool, which is suspected to have been caused by ruptured water main
PA
UK news in pictures 23 July 2021 Children interact with Mega Please Draw Freely by artist Ei Arakawa inside the Turbine Hall at the Tate Modern in London, part of UNIQLO Tate Play the gallery's new free programme of art-inspired activities for families
PA
UK news in pictures 22 July 2021 Festivalgoers in the campsite at the Latitude festival in Henham Park, Southwold, Suffolk
PA
UK news in pictures 21 July 2021 A man walks past an artwork by Will Blood on the end of a property in Bedminster, Bristol, as the 75 murals project reaches the halfway point and various graffiti pieces are sprayed onto walls and buildings across the city over the Summer
PA
UK news in pictures 20 July 2021 People during morning prayer during Eid ul-Adha, or Festival of Sacrifice, in Southall Park, Uxbridge, London
PA
In Wales, the highest temperature was 27.1C at Usk in Monmouthshire, while the mercury reached 24C at Fyvie Castle in Scotland's Aberdeenshire and 22.2C at Ballywatticock in Northern Ireland.
Greg Dewhurst, a Met Office meteorologist, said central and eastern England were the likely areas that could experience a maximum of 30C on Tuesday.
More widely across England and Wales, conditions will be in the mid-to-high 20s, while Scotland and Northern Ireland could see temperatures around 24C to 25C.
Mr Dewhurst said low pressure moving in from the southwest on Wednesday make it “less hot” in parts of Wales and Northern Ireland, but “hot air” will remain in central and eastern England and Scotland, bringing highs of 26C to 29C.
A location meets the UK heatwave threshold when it records a period of at least three consecutive days of daily maximum temperature levels meeting or exceeding thresholds which vary across the country.
Recommended October firebreak lockdown would be ‘last resort’ to save NHS, says government ‘Afghan children wore their best clothes’: RAF airman reflects on Kabul rescue flight Home Office and Kent Council face legal challenge over treatment of child migrants
These include 25C for Wales, Scotland and southwest England, 27C for southern and eastern England and 28C for London.
Additional reporting by Press Association