I know exposure to UV like we have here, will fade/peel a clear coat. The heat alone, I don't think so. I have seen cars stored in shade 11 years and paint/interior still good.
EDIT: Oxygen Oxidizes. No more: "oxygen" where there is hi heat and UV than anywhere else. Actually, smog, acid raid, do worse. Heat and UV don't oxidize, they do other things to a finish which may resemble oxidation.