What causes Peru and Chile to have an arid climate and desert vegetation along the coast?

Peru and Chile experience an arid climate and desert vegetation along their coasts primarily due to the cold Humboldt Current, which cools the air above it and reduces moisture. Additionally, the Andes Mountains create a rain shadow effect, blocking moist air from reaching the coastal regions. This combination of cold ocean currents and geographic barriers leads to low precipitation levels, resulting in the desert conditions typical of these areas.