Rainwater seeping into my Honda Civic? Why? How to fix?

I have a 2000 Honda Civic. And for about 6 months now I've noticed that rain water is coming in through an opening on the driver-side floor board. After it rains there appears to be a bit of water soaking my floor board. Maybe about 12-24 ounces. I tried to pull up the carpet and padding but it was attached pretty good and i didn't want to get to a point where i couldn't put it back together. And I tried to look underneath the car where the floorboard may have a hole. Didn't see any thing. I'm thinking its maybe coming from water running down from the windshield, but it the water only forms in the middle-left, which kinda eliminates it trickling down that way. Is there a channel or something that displaces rain water that I'm not aware of where it would seep up like mine?

Clogged up drains like moonroof drains, there are two drains under the windshield cowl, there are door and door body seals may need replacement. That are all of the possibilities I can think of for your situation. There was no TSB.

Stay inside the car with a flash light, all windows up and have someone with a garden hose or a high pressure car wash machine and see if you can spot where the water intrusion coming from. Just spray heavily around the moonroof, the windshield and the driver side window and door frame.

Normally, I've found a lot of water leak this way on any vehicle.

Check the caulking around the windshield.