I actually find it a lot more effective as the temp drops. The rocks, trees, etc. get colder and it allows me to run the ps32 at a higher level of red alert. When it's sorta warm, everything seems to want to show up red at the higher settings. I generally operate at the first level. Click once for white, two for black, and three for red alert. As it gets colder, I can use the scope at the fourth and fifth clicks more effectively. I get sharper resolution at those levels too. it's always important to not get any skyline involved. The deep cold of space makes for a huge differential. Kinda hard to look for coons with it because of that. Gets a little tricky, but it can be done.
I definitely like mine a lot more in the really cold weather.