Reminds me of a gig I had, performing for a civil war play, in the Fall when it was still pleasant during the day here in West Virginia, but nights get cold here in the mountains. And the dew clings to everything when the fog inevitably rolls in. This must have been closer to October because we were under an open tent (the band) but I was really concerned about my violin, because it was cold and wet. I remember plugging in a small electrical heating unit and covering myself with a quilt. I stayed warm, and the hot electrical air blew against the quilt and upwards to my violin, which I held under the quilt when I wasnt playing, and it got through the week of performances undamaged, thankfully.
I’ve played outdoors quite a lot. You have to always be mindful of staying out of direct, hot sun, don’t get rained on, don’t drop your violin in the camp fire and don’t set it down where someone will sit on it. 🙂