It's often difficult to determine whether or not a shingled roof needs to be replaced after a hail storm because damage is not readily evident to the average eye. Hail can damage your shingles, siding and gutters without any visible signs from the ground.
If your hail was golf ball size or larger---it more then likely broke through your shingle and caused bruising. If driven by high winds or if it hailed for more than a few minutes, your roof has more then likely suffered from loss of it's protective granules. Granules aren't just there for appearance purposes, they're there to protect the asphalt based roof product (the shingle). Asphalt and the sun do not mix. The sun will beat it up pretty badly. It doesn't take much of a hail storm to dislodge a bunch of granules, thereby exposing the asphalt and shortening the service life of your roof. If your roof has gone through a moderate to heavy hail storm---it is very important to have your roof inspected for hail damage. Loss of granules on the shingle will cause the organic-based center of the shingle to be exposed to the suns UV rays. This causes quick and serious deterioration to the shingle. It's easy to spot the damage when the hail actually puncture's the shingle---but, it's just as important to know when the shingle has been bruised. Ignoring the potential damage and allowing sun, rain, wind, snow & ice to beat against the damaged shingles can cause a serious continual cycle of damage to your roof and by the time you realize the damage has happened it may be too late to claim it on your insurance. Have the exterior of your home inspected. Better safe then sorry. Here's a few other enemies: