I did a few hours each night 2 nights in a row for Lulin 2 weeks ago. Both nights were rather gusty with temps according to NOAA in the high teens to mid 20s. Never saw a even a hint of frost on my scope though... Gotta love that!
The coldest apparent temp record for me would be about 15 years ago. I went solo camping for some celestial event, I don’t remember which one at the moment, some meteor shower I guess. Anyway, it was about 20F and clear, but it got very windy sometime after midnight. My small camp fire started blowing flat across the ground and had to be put out. The only thing that kept my 2 man dome from blowing away as morning approached was the dead weight of my body wrapped in 2 (yes 2) 30 degree bags. At times the tent was also just about flat on the ground as the wind seemed to get worse every time I roused a bit.
When I finally got up to go home, I had a huge surprise waiting outside. There was about a half inch of crystal clear ice on everything… except the tent. I remember that I had to work to get my truck’s doors open. I guess that maybe I don’t recall the reason that I was out to the dark site… because my brain froze while I slept. 