The answer is yes the temperature could affect the CD player's performance,specially on those hot california days,that's because as you might have knowledge all CD players plays the CD's through an laser beam,that laser beam its self becomes very hot,beside that the inner side of the dash turns very warm because of the proximity to the engine firewall & the trans temperature,plus the enclosed design of the dash,so i'll suggest you to have the head unit installed at the upper slot,you can aslo switch the cassette player to the lower slot & the CD player at the upper,it's much better,just to avoid any potencial issues.![]()