A “danger to life” heat warning has been extended by the Met Office for a further 24 hours, with a chance temperatures could hit 40C.
The amber extreme heat alert covers nearly all of England and eastern Wales and will now be in force from Saturday at midnight until the same time on Tuesday.
With the NHS already under pressure as the relentless heat drives more people to A&E, the Met Office has warned the impact on people and infrastructure will be widespread – with health consequences not merely limited to at-risk individuals.
“Population-wide adverse health effects are likely to be experienced, not limited to those most vulnerable to extreme heat, leading to potential serious illness or danger to life,” the forecaster warns.
It is likely that “substantial changes in working practices and daily routines” will be required, according to the Met Office, which told the country to brace for delays, closures and cancellations for those travelling by road, rail and air over the weekend as a result of the heat.
Officials have not ruled out Britain’s first ever national heatwave emergency – a decision that would be taken by the Cabinet Office.
According to the government’s official heatwave plan, other risks anticipated during a heatwave severe enough to merit a national emergency include issues at power stations, higher concentrations of air pollutants, classroom closures, and crop failures.
London Mayor Sadiq Khan has triggered a severe weather emergency response, typically activated when temperatures plummet to freezing in the winter, to support rough sleepers in the capital in the heatwave.
City Hall has written to all London boroughs and rough sleeping services to ask them to conduct welfare checks on vulnerable people and provide sunscreen, water and information about staying cool and safe in the high temperatures.
Southern parts of England have already been placed on a “level three” alert – one rung below a national emergency – by the UK Health Security Agency, a measure which requires health and social services to take action to protect vulnerable people.
The Met Office predicts that temperatures will likely exceed 35C on Monday and Tuesday.
But it believes there is a 30 per cent chance that the current heat record – of 38.7C set in Cambridge in 2019 – could be broken, while a small number of their meteorological models are producing forecasts of above 40C.
Heatwaves are the deadliest extreme weather event in the UK, and according to the Met Office there is an average of 2,000 heat-related deaths each year.
But scientists have warned that such events will only become more frequent and severe as a result of climate breakdown, and earlier this year the Met Office raised the threshold for weather to be considered a heatwave in parts of the UK to reflect the country’s warming climate.
You can follow the latest weather updates on The Independent’s heatwave blog.