Hmm, I don't recall that being much of an issue. If the sending unit has an LCD display, that might not work well in coldest weather. But so long as the signal transmits to where you are you should be good. I suppose the batteries might be affected by the cold if they're not new?
Let's see what the rest of the crew here says. I've only used (a Maverick) a couple times in colder weather and it wasn't a problem.