Europe's record-breaking heatwave left around 68,000 households without electricity in northwestern France on Wednesday, authorities said, in the country's first major power outage of the latest bout of extreme weather, as EDF shut down a nuclear reactor and reduced output at two others due to rising river temperatures.

“Record-shattering temperatures are feeding demand for air conditioning and driving surges in demand for electricity.”

A severe and sustained heatwave across Europe has triggered widespread deaths, shattered temperature records, and disrupted transport, work, and public...