Was the phrase “perfect storm” used much before the book/movie? It’s a hell of a great title. You’d think someone would have thought to use it before 1991.
The Port Arthur News used the term in this issue, referring to flooding in the Appalachians.
https://newspaperarchive.com/port-arthur-news-mar-20-1936-p-28/
There’s not much in the way of how often it was used, though.
When the movie came out, and perhaps earlier with the release of the book, there was mention of prior use of the phrase in some of the publicity releases. I don’t recall anything about Appalachian flooding, just references to other storms at sea and more figurative usage.
According to Wikipedia it has been around since 1718.
I have heard a brother of the story-telling trade at Naples preaching to a pack of good-for-nothing honest, lazy fellows by the sea-shore, work himself up into such a rage and passion with some of the villains whose wicked deeds he was describing and inventing, that the audience could not resist it; and they and the poet together would burst out into a roar of oaths and execrations against the fictitious monster of the tale, so that the hat went round, and the bajocchi tumbled into it, in the midst of a perfect storm of sympathy.
— William Makepeace Thackeray, Vanity Fair
But not in the meteorological sense until, supposedly, 1850; the search function at the UK Meteorological Office cannot find any such mention.