The worst-hit city was Rovinj, where trees were torn down, roads blocked, and dozens of yachts stranded.
Emergency crews worked through the night, with over 100 callouts reported in 24 hours.
Winds reached over 100 kilometres per hour, and more than 2,000 lightning strikes were recorded in just one hour.
Footage shows firefighters clearing fallen trees and damaged vehicles as cleanup operations continue.
The storm had calmed by Tuesday afternoon, but damage in some areas may take days to repair.
