Blame cold weather for nighttime smoke alarm chirps

If your smoke alarm started chirping in the middle of the night, the cold weather, not a broken alarm, is likely to blame. Overnight cooling drops voltage in batteries, the same reason phones lose charge faster in the cold. A battery nearing the end of its life can dip below the alarm's chirp threshold overnight. The chirping often stops once the house warms up, but it's best to replace the battery now.