San Francisco Frontiers - Italy on red alert as France, Portugal beat hottest May day record

Britain and France have already reported their hottest-ever May days this week as a "heat dome" brought sweltering temperatures usually unseen until high summer to western Europe.

Several people have died in both Britain and France, mostly in drowning accidents that authorities have linked with the baking heat, while Portugal's Health Minister Ana Paula Martins reported that the heatwave had caused a spike in hospitalisations.

The mercury peaked at 40.3C in Portugal's central town of Mora on Wednesday, topping the previous record of 40C from May 2001, the meteorological agency announced on Thursday, warning that the heatwave had a "high likelihood" of lasting into the beginning of June.

Italy has so far been spared the highest temperatures but on Thursday officials warned people in Rome and four northern cities to stay out of the sun.

"We're sweating a lot," said Spanish tourist Nana Martinez Garcia, trying to stay cool outside Rome's Colosseum on Thursday with temperatures hitting 32C.

"We're drinking a lot of water so we can cool down," she said, with her friend Maria Angeles Mellinas Tello chiming in that they were "staying in the shade" whenever they could.

The first red alert of the year in Italy -- which also covered Florence, Bologna, Brescia and Turin -- warned of "possible negative effects on the health of healthy, active people".

Scientists say human-driven climate change is amplifying such extremes, with weather events like heatwaves, droughts and floods becoming more intense and frequent.

- Tennis woes -

The worst of the heat seemed to have passed in Britain, but much of France continued to bake on Thursday.

Temperatures in the southwestern city of Angouleme hit a maximum of 37.8C, beating the records for May day temperatures just set on Monday and Tuesday, according to a provisional figure from Meteo France in the evening.

A school in the southwest was forced to shut its doors on Thursday and Friday afternoon after temperatures in the corridors reached 53C on Tuesday, causing pupils to get sick, a local official said.

"There was even someone who fainted and vomited," said Florian Deygas, an official in the Landes region.

Paris was expecting temperatures to hit 34C and remained on orange heatwave alert, national weather service Meteo France said, following record-breaking days in France on Monday and Tuesday.

Players at the French Open tennis tournament on the outskirts of Paris have been suffering from the heat, with one collapsing after winning a gruelling hours-long match.

Italy's Jannik Sinner, the red-hot favourite at the Roland Garros tournament, complained of dehydration, dizziness and nausea as he succumbed to the heat on his way to a shock second-round loss to opponent Juan Manuel Cerundolo.

Staff at the venue have been spraying the red earth courts with water after every set and once the day's matches are over, "we flood the courts, we soak them, so as to replenish with water the different layers that make up the clay", said head maintenance worker Philippe Vaillant.

In Spain, the national weather office Aemet issued heat alerts for Friday for parts of the northeast and north, where temperatures were forecast to soar to up to 37C.

The office said in a social media post that temperatures were "extraordinarily high" for this time of year across Spain, at levels typically seen in summer. It predicted that temperatures would drop noticeably next week.

"Go sit down in some air-conditioned restaurant, go to the museum, stay inside a little bit more during the hottest time of the day."

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G.Miller--SFF