Fierce thunderstorms and hailstorms around France left one woman dead and 14 people injured, ravaged vineyards and delayed flights.
Lightning hit the Eiffel Tower, without causing damage, and set roofs on fire east of Paris, according to local authorities.
Residents of southwestern France posted photos online of hail the size of tennis balls, and drivers in the Paris region shared images of flooded highways and daytime skies blackened by thunder clouds.
In Ille-et-Vilaine on Friday night, the fire brigade received almost one thousand calls in two hours.
"For the first time in 20 years, 65 mainland departments have simultaneously been under an orange advisory with an extremely strong episode of thunderstorms," France's Interior Minister, Gérald Darmanin, told reporters.
"The storms have prevented many people from using electricity. 15,000 are still without power. There were 3,500 interventions by 2,400 firefighters, whom I thank for their response," Darmanin said.
Thousands of households remained without electricity Sunday after the storms struck across France on Saturday, according to utility Enedis. Flights out of Paris' Orly Airport were temporarily suspended Saturday, and there were delays at Charles de Gaulle Airport.
A woman swept away by flooding was found dead under a car in the historic Normandy city of Rouen, according to Darmanin. The circumstances of the death were unclear.
In the Loire Valley, thousands of young people who were taking part in a huge scout gathering had to take refuge in the Chateau of Chambord as hail, thunder and lightning pounded the area.
The chateau director told public broadcaster France-Info that some children were treated for signs of hypothermia but no serious injuries were reported.
Rains also lashed Normandy beaches as veterans and others gathered for the 78th anniversary of the World War II D-Day invasion against the Nazis.