[keepitsimplestupid]

You got the outside wall temperature sensor not he outside air temperature sensor. There is a difference.

 

[firecontrol]

Some of the thermostats that have setback functions use the outdoor sensor to know how much lead time to put in ahead of your wake up temperature target.

 

[tpa-fl]

The only real way I can justify using an outdoor temp sensor would be if you have a heat pump with fossil fuel backup, then the HP will work when it's economically temperate outside, and will engage the backup when it knows the HP can't pull it off. Also, some stats will use the outdoor temp to adjust the indoor humidity so that you don't get excessive condensation on your windows in the wintertime, but being in Florida, I've never seen that happen.