On new years eve, I was trying to get a Big ole Viking Gas grill up to 250ish indirect to cook a prime rib. It was about -10 to -20F out without much wind. I was having trouble getting over 150, then my Maverick straight up quit on me. First it lost the LCD readout, then stopped sending the signal to the remote unit all together. After about 30 minutes inside it started working again.
I went with plan B and cooked in the oven until I was ready to reverse sear which I did out on the grill. I imagine with wind in those temps it will be tough to get too hot. But make sure you have a plan for temp monitoriing too!