if it only happens when raining and when in motion then the leak points to check are

1 the front wiper tray edges - which drain into their specific plastic tubes
2 the rear wheelhouse rubber plugs - this can literally flood your car with gallons of water when moving in water.

__________________
2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)