There are surfaces that need more attention than the once-a-year baseline. Driveways and concrete pavers in desert climates accumulate a particular kind of grime — a combination of tire marks, dust that's been wetted and dried repeatedly, and mineral deposits from hard water if you're irrigating nearby landscaping. High-traffic areas around entry points and garage aprons often benefit from a targeted wash two or three times a year even if the rest of the exterior is fine. Pool decks are similar — the combination of sunscreen, mineral deposits from splash-out, and dust creates a film that builds up faster than the surrounding hardscape.

One thing that's genuinely different about figuring out how often to pressure wash in a desert climate is the water quality issue. Desert municipalities typically have very hard water with high mineral content, and if you're pressure washing and letting the water dry on a surface rather than rinsing thoroughly and quickly, you can leave mineral deposits that are harder to remove than the original dirt. This is especially noticeable on windows and smooth stucco. If you're doing the work yourself, working in sections and wiping or rinsing before water dries is worth the extra effort. Early morning is better than midday for the same reason — surfaces and water heat up fast in desert sun, and hot water evaporates before you can clear it properly.

Stucco deserves specific mention because it's the dominant exterior finish in desert construction and it has its own quirks. It's porous, which means it absorbs fine dust at a level that smooth siding doesn't. A good pressure wash with the right nozzle — a wide fan tip rather than a concentrated stream — pulls that embedded dust out effectively. Too much pressure or too concentrated a stream can damage the surface, especially on older stucco that may have hairline cracks. Fifteen hundred to two thousand PSI is generally the right range for stucco; more than that risks forcing water into cracks and causing problems you didn't have before.

The broader point about how often to pressure wash in a desert climate is that you're mostly managing appearance rather than preventing biological damage the way you would in a humid environment. Moss and algae cause real structural problems if left unchecked on roofs and siding in wet climates — they hold moisture and accelerate decay. Desert grime is primarily cosmetic. That doesn't mean it doesn't matter — a dusty, stained exterior affects curb appeal and home value just as much as organic growth does — but it does mean you have more flexibility in timing and frequency without worrying that waiting an extra month is going to cost you structurally.