In the summer, the second floor of my house gets a lot hotter than the first floor.
I’ve never known how much hotter, but I have always suspected it to be a few degrees higher. My daughter sleeps in her room which is located on the second floor, for her afternoon nap. Even with the fan on, she sometime wakes up drenched in sweat. But, the temperature downstairs is comfortable.
This prompted me to install a wall switch plate thermometer on the second floor. Sure enough, on hot summer days, the second floor is about 4-5 degrees warmer than the first floor.
This allows me to properly adjust my programmable thermostat. In the winter time, since the upstairs will be warmer, I will reduce the heat in the afternoons.
Having a thermometer in different parts of your house is very handy and a wall switch plate is a convenient place to install it.