Proto-Indo-European thunder god
A Proto-Indo-European thunder god, reconstructed as *Perkʷūnos (Proto-Indo-European: 'the Striker' or 'the Lord of Oaks'), was the weather god in Proto-Indo-European mythology. The deity is thought to be associated with fructifying rains, and his name was probably invoked in times of drought.
Source: Wikipedia — Proto-Indo-European thunder god (CC BY-SA 4.0)