I'd ask your service dept about checking it; I don't know of any user-adjustable method, since we have no input to the OBD system.

I think the display is taken from the OBD inlet air temp sensor, which is not necessarily equal to the outside air temp- the air has already swirled around in proximity to the engine a little. With a larger temp difference in winter providing a more rapid temp change, the reading will be "more wrong" in winter than summer.