The hill at the southern end of this range was known in Elvish as Amon Sûl, which literally meant 'hill of the wind', but was translated as 'Weathertop'. If the same convention holds for the entire range of the Weather Hills, then their name implied that they were the 'windy hills', which would make perfect sense for an isolated range running through a flat surrounding land. On this association, we would expect the hills to have a Sindarin name something like Emyn Suil, though in fact we do not have a canonical Elvish name for the Weather Hills as a range.