In Southern California, the biggest enemy of exterior paint isn't rain. It's the sun. UV light breaks down the binder in paint over time, which is why south- and west-facing walls fade and chalk years before the shady side of the same house.
Heat and dry wind add to the damage. Stucco and wood expand and contract through hot days and cool nights, and dried-out caulk opens gaps where water gets in during the few storms we do get. Once moisture is behind the paint, peeling follows.
A paint job that lasts starts with prep: washing off chalk and dirt, scraping loose paint, filling stucco cracks, re-caulking joints, and priming bare spots. Then comes the right product for the surface, such as a quality acrylic exterior paint, or an elastomeric coating on stucco that tends to crack.
Timing matters too. Painting a hot wall in direct midday sun can make paint dry too fast and leave lap marks. We plan exterior work to follow the shade around the house when we can, so every wall gets a proper coat.