Leaking when it rains? Where in the hell is this water coming from?

I was going to say the bottom corner of the windshield, on passenger side. If you look at the corner of the windshield, I bet you can see some condensation. You can put a new gasket on, with no guarantees.
The car I have outside, I have a nice car cover, with a plastic tarp on top of it. Keeps the car pretty dry, with no water getting to the windshield.
Dont worry, it never rains in California,and the winters almost over. :)