The deaths, most from falling trees, were reported in Italy and Austria, and on the French island of Corsica.
Heavy rain and winds wrecked campsites on the island, while in Venice, Italy, masonry was blown off the belltower of St Mark's Basilica.
The storms follow weeks of heatwave and drought across much of the continent.
In Corsica, winds gusting up to 224 km/h (140mph) uprooted trees and damaged mobile homes.
Authorities there said a 13-year-old girl was killed by a falling tree on a campsite.