We have users in many cold air climates and have not had any issues with our controllers performing or being damaged. However, precautions should be taken to prevent water from entering the controller or blower then freezing. Additionally, even though it is very little, the controller generates heat, probably enough to keep itself functional if it is started at room temperature and put it in a container. Please note the LCD display on the controller is only rated to operate to -4 F.
If extreme weather conditions are expected or experienced during cooks, we have had users place a non-metallic bowl turned upside-down over the 100, 200, 300, or 500 controllers to protect it from water, sleet, snow, and freezing rain. Users have also fashioned an aluminum foil "tent" over and around the 100, 200, 300, or 500 blowers or 400 controller to prevent extreme wind and rain from infiltrating the blower and air intake vent.