Yes, The Plunge (including the chiller) can safely stay outside during the winter, even in freezing temperatures. However, it's important to keep the chiller running to prevent the water from freezing in the pipes. If you decide to unplug the chiller, make sure to properly winterize The Plunge by draining the tub and the chiller, and by removing the filter housing. When we went on vacation during the holiday season of 2022, I drained the tub and unplugged the chiller but forgot to also drain and remove the filter cartridge. Unfortunately, my filter housing cracked during a cold spell and had to be replaced. I could have avoided that repair by following the winterization instructions.