France, June 18 -- The latest heatwave to hit France is the second spell of unusually hot weather this year, after a scorching week in May broke records in half the country.

"A heatwave episode will gradually set in across the country this week," said Christelle Robert of Meteo-France, France's national weather service.

Temperatures hit 37C in some areas on Wednesday and could reach 40C in several regions by Sunday, including the Rhone Valley and the Île-de-France region around Paris.

Meteo-France added that the rise in temperatures would be made worse by the summer solstice - the longest day of the year - bringing more hours of sunshine.

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