The UK is braced for record-breaking temperatures of up to 40C on Wednesday and Thursday, prompting schools to close and people being urged not to travel.
Rare red weather warnings are in place for parts of England and Wales, as a “heat-dome” is settling over western Europe.
The Met Office issued red weather warnings for extreme heat for an area stretching from London to Swansea and Somerset to Birmingham from 9am on Wednesday to 9pm on Thursday.
During the peak of the heatwave on these two days, the temperature could come close to the UK’s all-time high of 40.3C, which was measured in Lincolnshire in July 2022.
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The latest heatwave is also expected to surpass the record for June of 35.6C set in Hampshire in 1976.
A combination of extreme heat and humidity could impact public health, infrastructure, power and water supplies, the Met Office said.
It can also cause heat-related issues for a range of sectors such as transport, energy and water supply.
There could also be an increase in water safety incidents during the heatwave, the agency said, as more people are likely to visit coastal areas, lakes or rivers.
On Tuesday the highest temperature logged was 34.6C in Wisley, Surrey, according to the Met Office.
Which areas will be worst affected?
Red heat health alerts have also been issued by the UK Health Security Agency (UKHSA) for the East of England, East Midlands, London, the South East, the South West and the West Midlands.
The agency has also issued amber heat health alerts for the North East, North West, and Yorkshire and The Humber.
These alerts are in place from 1am on Wednesday to 11pm on Thursday, and mean “adverse temperatures are likely to impact on the health and wellbeing of the population”.
Separate to the UKHSA’s assessment, the Met Office has issued its own red “extreme heat” warning covering parts of South Wales, the Midlands, the South West, South East, and London, which runs from 9am Wednesday to the end of Thursday.
An amber extreme heat warning, which, although milder, still warns of health risks, covers most of Wales and England – stopping just north of Leeds – from Wednesday to the end of Thursday.
Throughout all of Friday, an amber warning will remain in place in large parts of the North West, Yorkshire and the Humber, the East of England, the Midlands, London, and the South East.
A smaller amber warning, covering the southeastern corner of Great Britain, including Brighton, Reading London, Norwich and Skegness, will be in place on Saturday until 9pm.
How are schools impacted?
Almost 100 schools in Somerset will be fully closed on Wednesday and Thursday, according to Somerset Council.
And around 100 schools will be at least partially closed over the next two days in Buckinghamshire, along with 86 schools in Gloucestershire, according to council data.
Many schools in Horsham, West Sussex, are closing early on Wednesday and Thursday, with some setting pupils work to do at home.
St John’s Marlborough in Wiltshire said it would be shut all day on Wednesday and Thursday before re-opening on Friday.
Other schools in Sutton in south London and Haringey in north London have also been forced to close from Tuesday to Thursday.
Hampshire County Council has listed 35 schools which will at least partially close because of the heat this week, with a further seven in the Southampton area.
Children at some schools have been told they can wear PE kit rather than full school uniform, which can involve long trousers and blazers.
What about travel?
Transport bosses have urged people to avoid travelling on Wednesday and Thursday and are warning those that do to “prepare for a disrupted journey”.
National Rail warned of disruption to Gatwick Express, Great Northern, Southern and Thameslink services until Friday.
Greater Anglia has said passengers travelling, to, from or within the red warning zones “should only travel if absolutely necessary”.
Avanti West Coast said it planned to run fewer services than usual between Tuesday and Thursday, and that there was “a risk of further disruption”.
West Midlands Railway said passengers should check before they travel as extreme heat can cause rails to expand and buckle, so when temperatures reach certain thresholds, trains must run more slowly to keep services safe.
And Chiltern Railways said it had axed more than half its services until Friday “to ensure the safe operation of the railway”.
Eurostar has cancelled four trains planned to run between London and Paris on Wednesday and Thursday “due to expected adverse weather”.
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