I believe on most cars (early cars exempted), the temp sensor is behind the little "speaker grill" by the USB ports in the center console (its not a speaker grill, but it looks like that). On early cars, I understand the sensor is under the dash by the driver's right knee. If that grill is blocked by stuff in the center storage console, that could allow heat to build up inside the center console where the sensor is and that's what its sensing.
Our car is a 2013, Feb build, with the sensor near the driver's knee. If your sensor is there, here's the following things that could be causing this:
1) The sensor isn't in its holder anymore and is close to a component that gets warm and is sensing that temperature,
2) One of the airducts in the dash could be leaking warm air behind the dash, warming up that space, but not the cabin.
3) The sensor's bad.
Similar if you have the newer placement, but instead of dash airducts, it could be coming from the airducts for the back seats. An easy test of this one is to make sure the back vents are fully open. If that improves your heating performance, I would guess you've got warm air heating the center console instead of the cabin.