Wet Seat Belt - Leak

[mcasemo]

I have a 1995 325is and my driver’s side seat belt is getting wet after hard rains. The section that runs across my chest is the wet section, which recoils.

Any hints on where to look for the leak? Nothing seems obvious to me, but I’m pretty dim anyway. The floor is not wet, and it seems to only happen during heavy rains.

[drz]

Water must be leaking in through the sunroof. Open the sunroof and confirm that all four drain holes (one per corner) are clear.