Rear parking lights come on and drain battery

What is your question?

My Audio rear parking lights (only the rear) come on in the middle of the night. The first time I had to replace the battery, no big deal it was starting to fade. The second time the new battery held up and I was able to start the car no problem. The light switch was in the auto position for both of these times. What causing this? Does it have anything to do with the very cold temperatures at the time (20 F)?