Where you stand determines how important he is. In southern Iraq the barley grows because canals bring river water to it, and rain is a bonus that can also flatten the crop; in Syria and northern Mesopotamia the farming is rain-fed, and the god who brings the rain is the god who decides whether anyone eats. That geographical fact explains why Ishkur, the Sumerian weather god, is a middling figure in the southern pantheon while Hadad in the west is a supreme deity with kingdoms named after him.
Akkadian calls him Adad. West Semitic calls him Hadad or Haddu. An older reading of one of his titles gave the form Ramman, "thunderer", which is why the Hebrew Bible has Naaman apologising in advance for bowing in the house of Rimmon.
The blessing and the ruin in one prayer
His imagery is consistent from Sumer to Anatolia: a forked lightning bolt held like a spear or a bundle of arrows, an axe or mace in the other hand, and a bull either beside him or beneath his feet. The bull is for the bellow. Mesopotamian texts describe thunder as an animal's roar, and the god's voice and the storm are the same noun.
The prayers to him are unusually candid about what he is. He is invoked as the one who makes the furrows swell, the canal-inspector of heaven, the lord of abundance — and in the same breath as the one whose flood carries off the harvest, whose hail strips the field and whose storm topples the byre. There is no attempt to split him into a benevolent aspect and a malevolent one. Rain is not a good or an evil thing in this theology; it is a large force in the hands of someone who has not explained himself, and the correct response is to ask nicely.
Atrahasis uses him precisely this way. In the sequence of escalating punishments before the flood, it is Adad who is ordered to withhold his rain, so that the sky becomes iron and the fields yield salt; and when the flood comes, it is his roar that goes ahead of it. The same god does the drought and the deluge in a single poem.
Assur, Aleppo, and a temple with two towers
His Sumerian home was Karkara in the south, but his great cult centres are northern and western. At Assur, the Assyrian capital, he shared a double temple with Anu — a single complex with two sanctuaries and two ziggurats side by side, an unusual arrangement that Assyrian kings rebuilt repeatedly. At Aleppo, the storm god of Halab was one of the most powerful deities of the ancient Near East for two thousand years, receiving oaths in international treaties, and excavation of the temple on the citadel mound since the 1990s has uncovered relief panels showing him with his bull. Hittite kings, Mari's rulers and Aramaean dynasts all dealt with him, and his weapons were kept at Aleppo as objects that could be sent to a king to authorise a war.
The sky as an omen text
Divination in Babylonia had two presiding gods, invoked as a pair in the formal question put before every extispicy: Shamash and Adad, lords of divination. The sun sees; the storm signals. Whole tablets of the great celestial omen series Enuma Anu Enlil are given over to weather signs — thunder in a particular month, lightning in a specified quarter, the shape and colour of cloud, hail, the direction of wind, rainbows — each paired with a consequence for the king or the country. This is the mundane, working end of Mesopotamian religion, and it produced centuries of systematically recorded observations for reasons that had nothing to do with meteorology.
The god the Bible fights
Because the west made him supreme, he is the deity the Hebrew prophets contend with most directly — the Baal of the Canaanite and Phoenician material is the storm god Hadad, "Baal" being a title, "lord", rather than a name. The Ugaritic tablets from the Syrian coast give his mythology in full: a storm god who defeats the sea and builds a palace with a window in it for his thunder. His name is embedded across the biblical world in Ben-Hadad and Hadadezer, kings of Damascus, and in the place-name Hadad-Rimmon in Zechariah. The Aramaic Zakkur stele from the eighth century BCE has a king of Hamath recording that he called on his god in a siege and received an answer — one of the closest external parallels to biblical prophecy anywhere.
Points of confusion about the storm
Is he the same god as Baal, or a relative?
The same god, under a title. Hadad is the personal name and Baal the honorific, and Ugaritic texts use both for one figure. What differs is rank, not identity: in Babylonia he is a significant but subordinate deity, and in the Levant he is effectively king of the gods. Same profile, different weather.
How does he compare with Thor, Zeus or Indra?
Structurally he belongs to a very widespread type — a sky-and-thunder god with a weapon of lightning, a bull or a chariot, and a monster-fight in his back catalogue — and the comparison is genuinely useful as long as it does not slide into a claim of common origin. The Indo-European thunder gods share a linguistic inheritance with each other that Adad has no part in; the resemblance here is one of function and iconography, arrived at separately by cultures that all watched the same weather. The thunder gods compared page follows both the similarities and the point where the family tree stops.
Why is a bull the animal of thunder rather than something faster?
It is a sound argument before it is a visual one. The word used for thunder in these texts is the word for a bull's bellow, and hymns describe the god harnessing the storm-winds like a team. Once the pairing existed it became structural: the bull turns up under storm gods across the Near East and Anatolia for millennia, and the glazed brick bulls striding along Babylon's Ishtar Gate beside Marduk's dragons are his. That is a different animal from the murderous Bull of Heaven sent against Uruk, and the two should not be conflated — one is a storm's voice, the other is a drought given hooves.