Aircraft do suffer from a multitude of environmental induced damage during their lifespan.
Damage may be caused by hail, lightning, severe turbulence and sand/dust ingestion to name but a few. The price of rectification depends on the position/extent of the damage.
For example I recently had an aircraft that had encountered severe turbulence and this resulted in the aircraft undergoing a fairly heavy inspection in the Hangar. Although no damage was found the aircarft was out of service for a good 24 hours.