The operator of the French electricity grid Enedis has warned that with temperatures underground reaching up to 80C already, parts of the country's ageing infrastructure are under severe strain.
Speaking at a press conference on Monday, Enedis technical director Hervé Champenois said that "network failures, faults and even blackouts" are possible by Thursday.
He said: "The ground accumulates a lot of heat. When temperatures reach 40C at the surface, it can get up to 80C underground."
He added that France has around 15,000 kilometres of old underground electrical cables that are especially vulnerable to high temperatures, including under major cities such as Paris and Lyon.
He said that simulations run by Enedis based on the latest weather forecasts suggested that parts of the grid could fail by Thursday, although added that backup networks are in place.
