For others having the issue. It could be the following.
-small or big rip in the door weatherstripping seal around where you step into the vehicle.
-onstar antenna
-roof mount bolts
-degraded windshield seal
-wiring boot between driver kick panel and outside.
-small or big rip in the door weatherstripping seal around where you step into the vehicle.
-onstar antenna
-roof mount bolts
-degraded windshield seal
-wiring boot between driver kick panel and outside.