Garúa
The desert coast on the 1700 mile north south stretch is very dry: On average, it gets less than  of precipitation per year. Some areas may go without rain for many years.  Only the moisture condensed from the garùa clouds -- plus occasional El Niño events -- enables islands of vegetation to be present in the lomas dotted up and down the Peruvian and Chilean coasts.  Except for the lomas and river valleys draining the higher and more humid Andes the coastal desert has almost no vegetation.