The outage, which involved a transformer on the electricity grid, was related to extreme temperatures and did not injure anyone, the prefecture in the coastal department of Finistere said in a statement, AFP reported.
The incident took place around 9:00 p.m. (1900 GMT) on Tuesday in the commune of Ergue-Gaberic near the city of Quimper in Brittany, the prefecture added.
While teams from French grid operators RTE and Enedis had worked through the night to fix the issue, power is not expected to be restored in full until the end of the day at the earliest.
Up to 106,000 clients of the French power network were left without power by late Tuesday, as the continent’s sweltering heatwave pushed the country into its hottest day ever.
“For technical reasons, RTE will not be able to re-connect the affected households during the course of the day; connections will be made, at the earliest, by the end of Wednesday,” the operator said.
Finistere is one of 58 French departments under the highest red alert for extreme heat on Wednesday, with temperatures of 39C to 41C expected on Wednesday from Brittany to the Paris region.
The extreme weather is being driven by atmospheric and circulation patterns that keep hot air trapped in place for days, with these factors worsened by global warming, experts say.