Hi, late reply here..
I moved my shop this spring, and in my new shop I had no room for a spray corner. So I had to move the spraying equipment to my shed at home, a 3x3m with barn doors on one side. Unfortenately, all my 'fun' projects take forever these days, so the inverness green Epi ET-280 and some old radio cabinets have been nearly finished since mid summer. I recall some trouble in my late teens shooting rattlecan stuff wintertime, but can't remember what happened.
So, just recently I shot 9 clearcoats of nitro on my Epi - on November 2nd/3rd! Never shot nitro this late, it was -2 degrees celcius, some wind and 65% RH. That's about the worst conditions i have shot nitro in, and I think moisture is worse than low temperature. My favourite conditions when I had a place to shoot was 25 degrees and 35-40% RH.
But amazingly, the result was great, both on the Epi and the radio cabs (black nitro w. clearcoats). I'm not sure if it was luck, but there was no milk skin or any other problems. I really expected a mediocre result, but it came out great! Maybe I have just been too picky on the wheather conditions before..