…don't put your tongue on a cold metal light…
This reminds me of breaking snowmachine tracks loose from the ground at really low temps. I'd usually start the engines, then break the track loose and depending on how they were parked, often toss or drag them around to get them in the open and ready to go.
One day I got a firm reminder of the heat exchange difference between steel and aluminum. Most snowmachines have a steel bar in the bumper or cargo rack and aren't that bad to grab onto at -40, but the old Arctic Car Lynx had an aluminum tube back there and I ended up with what looked like actual burns across the insides of my fingers from holding one of them for too long. After that I really paid close attention to how long I'd grab the back of one of them without gloves when it was cold out. Zero, not really a problem, but probably -20 and colder was time to grab quickly, toss, and let go!
Point being, copper and aluminum lights will be the worst when it's cold, while titanium or steel are less bad, and plastic reigns supreme in some conditions.