Have you ever found your home air conditioning running when the outside temperature has already fallen below the temperature inside your house? I have. It's really irritating, and it wastes both money and energy.
The solution is simple, free and most of the time works fairly well.
Use IFTTT to set up a temperature alert for your zip code. Specify a temperature and how you want to be notified.
If you'd like to try it out, feel free to copy my "Open Windows" alert.