@ossobuco,
I don't think I ever used the term myself, but I heard it enough as a kid in the 70's. I seem to remember saying that to my wife a few times, but I say goofy stuff to her {or the kids} that I would never say to anyone else....I really don't speak that way. I have never, ever uttered the phrase, it's raining cats and dogs.....I've never called anyone a square either.
I have used Indian Summer on many occasions, but probably no more than I have said...false summer, as this type of weather is very common in my part of the country.