The short answer
Manufacturers rate asphalt shingles for decades, and that rating is calculated in a laboratory, not on the Gulf Coast of Florida. In practice a shingle roof here gives you noticeably less than the same roof would give somebody in Ohio, and tile and metal both outlast it by a wide margin.
We are not going to print a single number and pretend it applies to your house. Two roofs of the same age on the same street can be in completely different condition depending on which way they face, how the attic breathes, and whether the last repair was done properly. What follows is what actually drives the difference.
What wears a roof out here that does not wear one out elsewhere
Gulf Coast roofs age from the top down and the bottom up at the same time. UV load runs year round, so asphalt shingles lose their volatiles and turn brittle faster than they would further north.
Summer thunderstorms drive rain sideways under lifted tabs, and the humidity keeps decking damp long enough for rot to progress between storms. Salt carried inland from the Gulf pits unprotected fasteners and flashing.
Add the daily cycle of hot afternoons and heavy downpours, and every sealant joint expands and contracts. That is why a roof here fails at its details — flashing, boots, ridge, fasteners — far more often than it fails across the field of the roof.
A roof in this climate almost never fails across the middle. It fails at the flashing, the boots and the fasteners — the parts nobody can see from the driveway.
Material by material, realistically
Asphalt shingle is the shortest-lived of the common choices in this climate, and the one most affected by ventilation and by which slopes take the afternoon sun. An architectural shingle outlasts a three-tab.
Tile lasts a very long time as a covering, and this catches people out: the tile can be sound while the underlayment beneath it has failed completely. On a tile roof the underlayment is usually what you are actually replacing, and a roof that looks perfect from the street can still be leaking.
Metal is the longest-lived of the three here and handles wind-driven rain well, provided the fasteners and flashing details were done correctly. Its failure point is almost always penetrations and panel ends, not the panels themselves.
Manufactured and mobile home roofs are their own category and behave differently again — seams open, coatings chalk, and low slopes hold water. We cover those separately.
The age your insurer starts asking questions
For most Florida homeowners the roof's remaining life becomes an issue long before the roof actually leaks, because the carrier raises it first. Roof age is one of the things that decides whether a policy is written or renewed at all, and it is the item that most often causes a problem on a four-point inspection.
This is worth getting ahead of. A documented condition report, with photographs and an honest assessment of remaining life, is a far better thing to have in hand when the renewal letter arrives than a scramble afterwards.
Separately, how the roof is built affects your wind mitigation credits — the deck attachment, the roof-to-wall connection, whether there is a secondary water barrier. Several of those are decided the day a roof is replaced and are expensive to revisit later, so they are worth raising before the work rather than after.
How to tell where yours actually is
Age alone is a poor guide. Granules collecting in the gutters, shingles that look dark and flat where they used to be textured, lifted or curled edges along a windward slope, daylight or staining visible in the attic, and any soft spot underfoot are all worth more than the number of years.
If you are not sure, have someone look and put it in writing. A written report tells you whether you are looking at a repair, a few more seasons, or a replacement to plan for — and it is the same document that answers your insurer.