Rusting
 

http://i.imgur.com/ioOhnOu.jpg

So it rained pretty hard yesterday and has been raining for a few days, but this car has been through rain before and this has never happened. It's very ugly.. Any ideas about what caused it or the best way to fix it?

Totally fine. It's probably happened before and you didn't notice it. Hit your brakes a few times and it will come right off.

Yes that's completely normal. It will come off as soon as you use the brakes. It's caused from the brakes getting wet or some condensation forming on them and then the car sitting still for a little while.

Jeeze.. I was worried for a minute haha thank you both!

No worries I remember how I freaked out when I first noticed this on a car. :)

It's rotor oxidation. It's normal.

Mostly happens after you wash your car lol.

The way to get rid of it is to drive and use your brakes LOL.

totally normal! Whenever I wash my car after driving it the breaks look like that almost instantly due to the heat. All it is is oxidization from the minerals in the water. One drive later and they look nice n shiny like normal :D

The rotors aren't stainless so they rust pretty quickly. The rotors on my STI got pitted because it sat for a few months after being driven in heavy salt. If you're ever in salt, rinse the brakes off really well and go for a short drive before you put the car up.

Did the factory bother trying to mount the tires properly? That's a lot of wheel weights. Wouldn't it make more sense to have the TPMS on that side for extra weight?

Only wash the car before going for a drive.
If it is parked with wet discs , they will rust.