Using the camera in really cold weather can cause a battery to perform below its projected lifespan. If the camera is stored in a cold location, the battery will not hold its full charge either. If you must work in cold conditions with your camera, try carrying the battery in a pocket close to your body, where the heat from your body will allow the battery to stay a little warmer than it would inside the camera, which will allow it to maintain its full charge for a longer amount of time versus keeping it inside a cold camera for an extended period of time.