There are several components used to adjust the temperature of the cabin relative to the outside temperature. There is a thermometer behind the front bumper, an air intake to the right of the steering wheel, and a solar intensity sensor at the front of the dash. As I understand it, the solar intensity sensor is used in conjunction with the internal thermometer to detect the temperature you are probably feeling (sort of like a wind chill adjustment but for heat), and compares that to the external temperature to maintain the setting you specify. The external thermometer, due to its position behind the bumper, is prone to high readings if the car is not moving or is in slow traffic on hot asphault. Correct me if anyone knows better.
it's possible that it doesn't use the outside temp for anything other than reporting it. Or they might use it to bias the inside temperature, figuring that if it's 110 outside, the inside of the car is going to heat up a lot faster at slower A/C fan rates so they might use it to adjust the temperature curve. Who knows other than the people that designed it ;-)