In the northwestern city of Rennes, 74-year-old Daniele Dupont tried to stick to the shade as she walked her dog in 27C on Monday morning

"I'm going to close the shutters. I won't be going out this afternoon," she said in the capital of the Brittany region, across the Channel from the United Kingdom.

Parts of Brittany were under a so-called yellow heatwave alert, urging caution, for a second day on Monday.

A Meteo France spokeswoman told AFP that the warning first issued for Sunday was "the first yellow heatwave alert to be issued in May since the system was created in 2004".

On Sunday "record high maximum temperatures for the month of May" were felt in at least 10 locations, including the northwestern seaside towns of Lorient and Noirmoutier, Meteo France said.

Paris on Saturday notched up its first temperature above 30C of the year, hitting 31.9C.

A man died during a 10-km running race in Paris on Sunday, civil defence services said. Local newspaper Le Parisien reported he was 53 years old and suffered a heart attack.

Ten more runners had to be taken to hospital in critical condition after a race in the capital's suburb of Maisons-Alfort, the authorities said.

In Rennes, Bernard Siffert, 66, wasn't taking any chances.

"I went for a run yesterday and did 15 km at 7 am instead of 10 am like I usually do," he said.

Scientists say that recurring heatwaves are a clear marker of global warming and that these heatwaves are set to become more frequent, longer and more intense.

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