Speaking earlier of gridiron bons mots, we linked to this page from Google Books. The page is from The Quote Verifier, a book by Ralph Keyes. (Mr. Keyes seems to have turned out a nice variety of books on writing, misquotes, wit and wisdom, and so forth. He also collects chrome toasters.)
Anyway, at the bottom of that page about Robert Benchley and dry martinis, we found a separate entry about the quote “The coldest winter I ever spent was a summer in San Francisco.” Keyes says it has been attributed to Robert Louis Stevenson, H.L. Mencken and others, but especially to Mark Twain.
Mark Twain is the guy I always heard it attributed to when I lived in the Bay Area, and I heard it attributed to him a lot. But Keyes says “Not so!”
No one has ever found the comment in any of Mark Twain’s works. In Roughing It, Twain called San Francisco’s climate “mild and singularly equable… It is no colder, and no warmer, in the one month than the other.”
Keyes’s final verdict is that the original author is unknown, though Twain may have adapted it. Thus dies another lively phrase — although let’s face it, Twain has plenty of others to fall back on.