Paris on Thursday baked in an all-time high temperature of 42.6 degrees Celsius (108.7 Fahrenheit) as a ferocious heatwave smashed records across northern Europe, sparking concerns about public health and causing new misery for rail travellers.
As records also tumbled in Belgium, the Netherlands and Germany, Paris beat the previous top of 40.4C set in July 1947.
Trains have been slowed in several European countries to avoid damage to the railway networks. French national operator SNCF urged travellers to delay journeys planned for Thursday, while German railway company Deutsche Bahn offered travellers a chance to change tickets free of charge.
In the sweltering French capital, authorities warned people to keep an eye on those living alone.
At the same time, the scorching weather spelled misery for millions of commuters on public transport.
"It's so hot in the metro, it's unbearable. There are so many people, no air conditioning and everyone is on top of one other," said Paris commuter Petra Ulm, 34, a clinical researcher.
The heatwave, which was expected to ease up on Friday as rain and thunderstorms move in, again focused public attention on the problems caused by climate change.
'Great day on the beach'
In Britain, temperatures reached 38.1C in Cambridge, only the second time temperatures over 100 Fahrenheit have been recorded in the UK, weather services said. It was still below the UK's all-time high of 38.5C.
Those lucky enough to be by the sea could still enjoy the weather.
"It's obviously not so good for some people, but if you've got the day off and young kids then it's great for a day on the beach," said Graham Clarke, 50, an insurance agent, enjoying the sands of Broadstairs in southeast England.
In the Netherlands, a new high Thursday of 40.4C in the south broke a record dating back to 1944.
In Amsterdam, crowds jumped into a central square fountain, while municipal workers sprayed water on bridges over the city's famed canals to stop metal structures deforming in the heat.
"I'm just trying not to move too much," said Serona Methorst, a 19-year-old Dutch student sitting under a tree with friends. "We are so used to a colder climate, people are really disturbed by this weather."
In the centre of the country, Dutch police jokingly urged criminals not to plan any heists during the heatwave.
"It's tough to work now, not just for you but also for us," the police posted in a Facebook message. "Stay at home, turn on the air-conditioning."
On Thursday, Germany again hit a national record of 41.5 C in Lingen, western Germany.
The Grohnde nuclear plant in western Germany will temporarily shut down on Friday as a way to protect the environment, its operator said. Water used to cool the reactor is poured back into rivers and the shutdown is meant to protect already overheated river ecosystems.
Belgium on Thursday also reached a new record high of 40.6 degrees Celsius, on the Kleine-Brogel military base, in northeastern Belgium.
Two suspected drug smugglers had to call police in the Belgian port city of Antwerp after becoming trapped in a shipping container filled with cocaine, prosecutors said.
Eurostar and Thalys rail services from Brussels to London and Paris also experienced major delays and cancellations after a cable failure the day earlier.
"I ask everyone who can avoid or delay their journeys to do so," said French Environment Minister Elisabeth Borne, advising workers who could do their jobs at home not to go to their offices.
The northern third of France, including Paris, was under a red alert while the rest of the country had a yellow warning and water-use restrictions were in force.
In Austria, a three-year-old child died of dehydration after falling asleep in a car parked in full sunshine at the family farm, local authorities said.
'Look after others'
France remains haunted by the early summer of 2003 when 15,000 deaths were blamed on the heat and the authorities were hit for not mobilising fast enough.
"We need to take care of ourselves but above all others, especially those who are alone, and be able to detect the first symptoms of heatstroke," said Prime Minister Edouard Philippe.
Local authorities have placed restrictions on water usage in many areas due to drought-like conditions that have seen ground and river water levels fall dramatically.
A June 26-28 blast of heat in France was four degrees Celsius hotter than an equally rare June heatwave would have been in 1900, the World Weather Attribution (WWA) said this month.
One study by the Swiss Federal Institute of Technology said the deadly weeks-long heatwave across northern Europe in 2018 would have been statistically impossible without climate change.