Tarḫunna or Tarḫuna/i was the Hittite weather god. He was also referred to as the "Weather god of Heaven" or the "Lord of the Land of Hatti".
Tarḫunna is a cognate of the Hittite verb tarḫu-zi, "to prevail, conquer, be powerful, be able, defeat"; from the Proto-Anatolian weather god *Tṛḫu-ent-, "conquering"; ultimately from PIE *terh2-, "to cross over, pass through, overcome". The same name was used in almost all Anatolian languages: Luwian Tarḫunz-; Carian Trquδ-; Milyan Trqqñt-, and Lycian: Trqqas (A), Trqqiz (B).
Norbert Oettinger has argued that the functions of the Anatolian weather god ultimately come from the Proto-Indo-European god Perkwunos, but that they did not preserve the old name to coin instead the new epithet Tṛḫu-ent- ("conquering"), which sounded close to the name of the Hattian Storm-god Taru.
As weather god, Tarḫunna was responsible for the various manifestations of the weather, especially thunder, lightning, rain, clouds, and storms. He ruled over the heavens and the mountains. Thus it was Tarḫunna who decided whether there would be fertile fields and good harvests, or drought and famine and he was treated by the Hittites as the ruler of the gods.
Tarḫunna legitimised the position of the Hittite king, who ruled the land of Hatti in the name of the gods. He watched over the kingdom and the other institutions of the state, but also borders and roads.
Tarḫunna is the partner of the Sun goddess of Arinna. Their children are the gods Telipinu and Kammamma, the goddesses Mezulla and Inara, the Weather god of Zippalanda and the Weather god of Nerik.
As a result of his identification with the Hurrian god Teššup, Tarḫunna is also the partner of Ḫepat (who is syncretised with the Sun goddess of Arinna) and the father of the god Šarruma and the goddesses Allanzu and Kunzišalli.
His siblings are Šuwaliyat (identified with the Hurrian Tašmišu) and Aranzaḫ, the goddess of the Tigris river.
Tarḫunna was the chief god of the Hittites and is depicted at the front of a long line of male gods in rock reliefs at the sanctuary of Yazılıkaya.