Why is the passenger side of your car floor soaked when it rains but there are no wet spots on the roof or windows?

Answer

Simple, you have a leak. Suspect that it is leaking from the cowl. Check the drain for the condenser and see if it is plugged. Check for debris below the window in the channel.

if you have a sunroof, sometimes the drain hose gets clogged and water will back up into the car. It can run down the inside of your A pillar and end up in the floor board. Similarly, if it happens when you run the A/C, the condensation drain hose could be clogged and backing up into the floor.