My car has lived in California all its life and when I got it about 8 years ago, the only places that it had more than service rust were:

1) Above the door windows (the somewhat salty air from the ocean collected there every time the night dusk fell)
2) Bottom of the rear quarters and in back of the rear wheelhouses
3) Under the chrome trim on both the windshield and the back window (both windows leaked)
4) I don’t know how to describe this area, but it's where the leaves and dirt pile up that came through the cowl (it's next to the kick panel vents).

That's it. No rust anywhere else.