If you're going to leave the bike outside full time on a college campus, get a single speed coaster brake bike and pedal harder on the hills- you'll get a good workout, and impress the ladies with your awesome quads.

Seriously, leaving any bike outside is not good for it, even in southern California. It even rains in SoCal once in a while in spite of what they tell you, and your chain will rust and the chain lube will wash away. When that happens, the chain links and pins start to wear rapidly, and your derailleurs won't sift gears properly.

Any college campus is a magnet for bicycle thieves, just because there are so many bicycles around. If they can't steal the whole bike, they'll take the wheels, seat, or whatever else they can find, until they've stolen enough stuff to make a complete bike that they can sell for the price of a fix. The best defense is to ride a crappy bike that isn't worth stealing, and park it next to the nicest bike you can find when you leave it somewhere.

A single speed coaster brake bike will require much less maintenance than anything with gears, so you'll have more money for textbooks, partying, and maybe even buying a nice bike when you have a safe place to keep it.