Some times now when its really cold out and my car has been sitting the display for the bose head unit wont light up but it will play and then a few seconds later it lights up. What could this be?

 

crappy Clarion deck with BOSE written all over it?
Replace it. I've said it before (as have many others), the factory BOSE (Clarion) deck sucks and should be replaced, not troubleshot (troubleshooted?... nah, troubleshot).

Justin