Temperatures have hit a record high for the UK amid the sweltering heatwave, the Met Office said.
The provisional temperature of 39.1C at Charlwood, Surrey, beats the previous national record of 38.7C seen in Cambridge in July 2019.
But the record is unlikely to hold for long, as the Met Office is forecasting temperatures to reach as high as 41C on Tuesday in some parts of eastern England.
Much of England and Wales are under a “red” extreme heat warning until the end of Tuesday, with the heat causing disruption on transport networks and the risk of serious health impacts.
It comes after UK experienced its warmest night on record on Monday as the extreme heat saw temperatures remaining in the mid-20s in some areas.
Rail services have been heavily disrupted on Tuesday, with no services into or out of London Kings Cross all day, no Thameslink or Great Northern trains north of London, and only very limited services on East Midlands Railway.
There are also very limited and disrupted services running into and out of London Euston, on Avanti West Coast and West Midlands Railway, and London Marylebone on Chiltern Railways, and temporary speed restrictions in the face of the risk of buckling rails.
Transport Secretary Grant Shapps conceded the UK’s transport network cannot cope with the extreme heat and said issues on the rails and roads will continue for decades during such heatwaves.
Climate change is making heatwaves more extreme, frequent and likely, and experts warn the UK needs to adapt homes, hospitals, schools and transport networks to a future of more searing heat.
Much of Europe is also baking in record-breaking heat, which is fuelling wildfires in a number of countries.
The Supreme Court in central London was closed to visitors on Tuesday because of the temperatures and an air-conditioning fault, while many schools remained shut for a second day in the face of the extreme temperatures.
On the roads, figures published by location technology firm TomTom suggested commuters were heeding warnings not to travel unless necessary, with the level of road congestion at 9am on Tuesday lower in several cities than at the same time last week.
An East of England Ambulance Service spokesman said the service has detailed plans in place for dealing with the extreme hot weather.
He added: “We have seen above-average call numbers since Monday afternoon.
“Demand on our service is very high and, even when the temperatures drop, we expect to still being seeing an impact from heat-related illnesses into the weekend.
“Please continue to follow guidance during this period of hot weather and only call 999 in life-threatening emergencies,” he urged.
Met Office meteorologist Annie Shuttleworth said it is “extraordinarily unusual” to see temperatures in the 30s by the morning rush-hour in the UK.
She said the high overnight temperatures had led to a very warm start to the day, and added: “We’re looking at the maximum temperatures somewhere between 40C-41C, and that’s looking to be across the Lincolnshire and Yorkshire region.”
Britons have been urged to stay inside during the hottest period of the day, between 11am and 4pm, and wear sun cream, a hat, stay in the shade and keep hydrated with water – and there are warnings about swimming in lakes, rivers and reservoirs.
The Met Office has also issued a yellow warning for heavy showers and thunderstorms over much of the South East and eastern England which may bring disruption during Wednesday afternoon, as temperatures drop for their current searing highs.