Britain was on course for its hottest day on record on Monday with temperatures forecast to hit 40C for the first time, forcing train companies to cancel services and health authorities to put more ambulances on standby.
Much of Europe is baking in a heat wave that has pushed temperatures into the mid-40s Celsius in some regions, with wildfires raging across tinder-dry countryside in Portugal, Spain and France.
Britain’s government triggered a “national emergency” alert as temperatures were forecast to surpass the 38.7C (102 Fahrenheit) recorded in the Cambridge University Botanic Garden in 2019 on Monday and Tuesday.
“We’ve got a difficult 48 hours coming,” Kit Malthouse, a minister in charge of government coordination, told the BBC.
London’s Underground metro network imposed temporary speed restrictions on the network for Monday and Tuesday, meaning it would run a reduced service with journeys taking longer than normal. It urged commuters to only travel if essential.
The national rail network also urged passengers to stay at home, and said some services – including a key route between northeastern England and London – would not run during parts of Tuesday.
Jake Kelly from Network Rail said he hoped normal operations would resume on Wednesday, when temperatures are forecast to fall, but that would depend on “the damage that the weather does to the infrastructure over the next couple of days”.
Some schools were due to close earlier than usual on Monday.
The Health Security Agency (UKHSA) raised the heat health warning to Level 4 for England for Monday and Tuesday.
Britain’ Meteorological Office defines a Level 4 alert as a national emergency, and is used when a heat-wave “is so severe and/or prolonged that its effects extend outside the health and social care system. At this level, illness and death may occur among the fit and healthy, and not just in high-risk groups.”
The Met Office said “substantial” changes in working practices and daily routines would be required and there was a high risk of failure of heat-sensitive systems and equipment, potentially leading to localised loss of power, water or mobile phone services.
Malthouse said the government was prepared for the extreme weather and would seek to learn lessons from it.
“We definitely need to adapt the way we build buildings, the way we operate and look at some of our infrastructure in the light of what seems to be an increasing frequency of these kinds of events,” he told BBC Radio.
France also braced on Monday for what could become one of the hottest days ever recorded with temperatures reaching 40 degrees Celsius in coastal regions cherished by tourists, as wildfires intensified in the west and south.
“The peak of this heat wave is expected Monday,” MeteoFrance said in a statement, forecasting temperatures between 40 and 42 degrees – and “higher in some local areas” across France’s western Atlantic coast.
“The day could become one of the hottest ever recorded in France,” it said, adding that temperatures could edge towards an unprecedented 40 degrees in the Brittany port of Brest in the country’s northwest.
It will become clear later on Monday whether a new national all-day average temperature record, now standing at 29.4 degrees reached from the historic heat waves of 2003 and 2019, will be set.
Thick plumes of smoke could be seen from famous Atlantic coast beaches close to the towering Pyla sand dune near Arcachon as strong winds and high temperatures kept fuelling wildfires. Interior Minister Gerald Darmanin sent three additional water-bomber planes to the region.
Fires in the region have spread over 14,000 hectares (34,595 acres), the local state prefecture said in a tweet on Monday morning, adding that there were reports of injuries so far.
France on Sunday issued red alerts, the highest possible, for several regions, with residents urged “to be extremely vigilant”.