As shingles get older and get exposed to the elements, they will start to deteriorate. This could be seen in numerous ways that are not always visible from the ground level. It normally takes someone to get on top of the roof or conduct a drone roof inspection to get a closer look at the condition of the shingles.

When your roof is exposed to various harsh weather conditions such as storms with high winds or large pellets of hail, the deterioration of materials is accelerated. High winds can lift poorly installed or old shingles causing them to break off and fall. Hail pellets that are larger than 1" in diameter could cause some serious divots in asphalt shingles that could be a entry point for potential leaks. 

If the drainage systems on your roof are not doing their job and clearing the surface of water, the moisture build up could create biological growths or wear down your roofing materials. Other issues like structural damage or loose flashing can be a threat to the stability of your roof when the more extreme storms come.