Yahweh is not thought to be a native Canaanite god at all, but rather a foreign import from North Arabia who later replaced Baal (his counterpart as a storm god) and merged with El. This is known as the Kenite Hypothesis, based on evidence from archaeology and early layers of the Bible that associate Yahweh with areas South of Israel.

Some of this evidence includes: First: Moses discovering Yahweh worshippers in Midian (whom he marries into) Secondly, Yahweh's holy mountain (Sinai) being located in North Arabia (not the Sinai peninsula). Third, Yahweh being associated archaeologically with Teman (an area of Edom) in an inscription at Kuntillet Ajrud). Fourth are Late Bronze Age Egyptian inscriptions about the "Shasu of Yhw," nomads of North Arabia. Finally, the total absence of the name Yahweh in Canaanite records before his later appearance in the Iron Age.

By this hypothesis, Yahweh would have been brought by traders from North Arabia into Israel (before it was Israel) and he would have replaced Baal as one of the sons of El in the local version of the Canaanite pantheon. Later, via various religious reforms, he would have merged with El himself and then eventually absorbed all qualities of all gods, replacing the need for their existence in Israelite ideology. This then turned into outright rejection of the existence of other gods.

The latter part of that last paragraph is pretty standard stuff, but the Kenite Hypothesis, while very popular nowadays, is not proven. However, unless we get some kind of smoking gun (like an inscription showing Yahweh was a native Canaanite god in the Bronze Age or an inscription that says something like "we brought Yahweh from Edom and/or Midian") it remains educated conjecture.