Italy has issued a red heat warning for the capital Rome, while Portugal and France reported their hottest May days, as Europe struggles with a heatwave that has smashed records across the continent.
Britain and France reported their hottest May days this week as a "heat dome" brought sweltering temperatures to western Europe.
Several people have died in Britain and France, mostly in drowning accidents that authorities have linked with the baking heat.
Portugal's health minister Ana Paula Martins reported that the heatwave had caused a spike in hospitalisations.
Temperatures reached 40.3C in Portugal's central town of Mora yesterday, topping the previous record of 40C from May 2001, the meteorological agency announced, warning that the conditions had a "high likelihood" of continuing into next month.
Italy had been spared the highest temperatures but officials have today warned people in Rome and four northern cities to stay out of the sun.
The country's first red alert of the year - which covers Florence, Bologna, Brescia and Turin, as well as Rome - warns 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. It comes days after an Irish record for the highest temperature in May was broken.
Much of France continues to bake too.
Temperatures in the southwestern city of Angoulême hit 37.8C, beating the records for May, set earlier this week, according to a provisional figure from Météo France.
A school in the country's southwest was forced to close after temperatures in the corridors reached 53C, causing pupils to be ill.
Paris, where temperatures could reach 34C, remains under an orange heatwave alert, Météo 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, favourite for the men's title, complained of dehydration, dizziness and nausea as he succumbed to the heat on his way to a shock second-round loss to Juan Manuel Cerundolo.
Staff at the Roland Garros venue have been spraying the red earth courts with water after every set.
Head maintenance worker Philippe Vaillant said that, 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".
In Spain, the national weather office Aemet has issued heat alerts for tomorrow for parts of the northeast and north, where temperatures are forecast to soar to up to 37C.
Temperatures are "extraordinarily high" for this time of year across Spain, at levels typically seen in summer, the service said.
It predicted that temperatures would drop noticeably next week.
