Best definition
Someone on TV who guesses what’s going to happen with the weather.

(imagine a backwards-ass country fuck accent): Honey, the weatherologist says there’s a 69% chance of thunder showers, with a 420% chance of embedded supercells.
weatherologist: define #2
A person who studies meteors. (Looking for weather? See meteorologist.)
My friend is a weatherologist and he predicts a meteor shower will occur in five days.