This has been raised in another Q & A forum with mainly US participants, and the general tenor of the answers was that there are several other places in the USA which better qualify for the dubious accolade. Unfortunately I can't find it now to provide a link. The why would be explained by local climatology and geography - winds being channelled along valleys and the like.
I heard an explanation for this, and it has nothing to do with the weather. It was a term developed to describe the nonsense that local politicians were talking.