Does cold weather affect motion sensor lights going on and off?

Answer 1

Yes, the temperature definitely affects motion sensors.

Motion sensors don't exactly detect motion. The sensor chip is very sensitive to Infra Red signals given off by all objects in front of the sensor. Basically, it really senses temperatures.

When it is cold outside, a person, dog, or WARM car will all be much warmer than the surrounding background. Generally, a motion sensor will be much more sensitive in cold weather. It may turn on from something warm moving hundreds of feet away, like a truck, making you think it is turning on all by itself.

On a HOT day, on the other hand, a person or dog may not be that different in temperature than the background. In this case, a motion sensor may fail to detect motion.