My daughter owns a 2000 oldsmobile alero. Recently she has leak on the drivers side which enters the car behind the dash. I have checked the gasket around the door which seems intact.
Check the drain tube for the HVAC system. If it’s clogged rain will get into the car. Another common problem is clogged sunroof drains, which will also allow water into the car.
May also be a leaking windshield seal.
And one more the area under the grill in front of the windscreen, may also have a blocked drain.