The few violent days an LA roof is judged on
A Los Angeles roof spends most of its life under conditions that ask almost nothing of it, and that is exactly what lulls homeowners into trouble. The roof that has shrugged off a year of mild afternoons has not actually been tested, because the test is not the gentle weather, it is the Santa Ana that rakes the city a few times a year and the atmospheric river that parks over it for a weekend each winter. Those events arrive infrequently enough that an owner can go years without one really landing on their street, and then one does, and the roof is suddenly being asked to do the one thing it was built for, all at once, after years of quietly aging in the sun.
This is why we judge a roof by how it will perform on its hardest day rather than how it presents on an easy one. A composition roof whose nails have crept out a quarter inch over years of thermal movement looks completely normal from the ground and holds perfectly well until a gust gets under the lifted edge and peels a course. A flat roof whose flashing has hardened looks dry until wind-driven rain is forced sideways under it. Reading a roof for those failure modes, the ones that only show up under load, is a different skill than glancing at a roof on a clear day and calling it fine, and it is the skill the LA climate actually demands.