WHO "INVENTED" THE CLEAR SKIES SALUTATION?

Here's a challenge for you. In 1970 I wrote a show called Sky Scene Seventy for Vancouver's HR MacMillan Planetarium. In that show, there's a little dialog in which an astronomer greets another with the salutation, "Clear Skies!" The idea for the salutation just jumped into my head. I don't recall ever hearing anyone use it until I put it in the fictitious astronomer's mouth. I make no claims to "owning" it, or even "starting" it. I'm quite indifferent in that respect. But I've noticed how widespread it now seems to be, and I'm only curious to know whether anyone can confirm an example of its use before January 1970. I'll quite happily acknowledge its precedence.