Temp is irrelevant as long as the temps are changing as they do in the desert. The scope resolution is based on a contrast of thermal radiation from nearby objects. When there is a lot of humidity or fog and temps tend to balance out, the view gets muddy. Cold air does create much bigger contrasts and you can turn down the gain and really see well.
Hotter temps do create thermal currents that obscure, not much of a problem at night.
There is still a window of time at sunrise and sunset that viewing is difficult.
I try to stay current with the tech in my fiction writing. In my latest I'm working on, the protag is a former Marine, who uses a monocular night scope and an IR pointer on his rifle. If you get time, see if I make too many errors here. It's been decades since I was an operator.
"Castigo Cay," extended excerpt.
