I see weird white fog showing on my windshield when I drive in the morning and rainy weather. The fog also shows on my dads 2002 Legacy Wagon. When a fog goes on. Its even hard to remove it using wiper blades. The fog is on the outer side of the windshield and can be only removed by blowing hot air from the inside, which is a *************** when its hot outside. Could somebody please explain this problem to me, because I have no idea what it might be.

This happens because you are probably running your defroster on cold, when the defroster is on the AC is also running no matter the tempeture and you are blowing very cold air right at the glass. What you are seeing is the condensation forming just like on a cold glass on a humid day. A few things can be done, usualy just using the front vents and not making the cabin frezing cold takes care of things, if you must use the defroster set the tempature somewhere in the middle, it doesn't have to be hot but it can't be a lot colder then the outside air. I've noticed riding in friends cars on raining humid nights they often do this, and can't figure out why what you are describing is happening.

try rain-x, it works.

Yep, Rain-X is the business.

 

I agree with Smpol about the AC thing.