Did a 47?F outdoor gig 28 years ago (Golden, CO in mid-March), but fortunately A) it was sunny and B) I was the stage manager. I didn't have any problems, but the talent suffered (ever see someone try to play trumpet with heavy gloves on?).
This past weekend I did sound for a tent gig; 55-60? and damp (no precipitation during the show, but it had been drizzling all day). I was OK for $100 and working my ears, not my fingers, but you really don't want to do this for free, Greg.
Peter