So after a nasty rain, I noticed that there were water vapors on the inside of my headlights. What's the best way to prevent vapor from forming in the inside?

 

I'm guessing that there is a seal that has failed. I can't remember if there is a rubber gasket or if it's sealed only by silicon sealant. Someone who has done the cleared corners would know because they have to break into the casing to clear the corners.

 

The case itself is sealed with silicone. The bulb assembly has a rubber gasket. If you pull the bulb, it will help dry out the condensation. If you leave the condensation in there, the water will pool down at the ballast and corrode the contacts, shorting the ballast. The ballast is very expensive.

Have you had the headlight assembly apart? Like to do some smoked or clear lenses?