The climate of coastal northern Chile ranges from semi-arid to hyper-arid. The Atacama Desert in far northern Chile is one of the driest places on Earth. The region's aridity is due to its physical geography: the high Andes mountains to the east block moisture-laden air masses from reaching the Pacific coast, and the cold Peruvian current and offshore upwelling in the Pacific Ocean strengthen a persistent stable air mass. This stable air limits cloud formation. Stratocumulus, or layered, clouds do form and a cover of fog, known locally as the camanchaca, often flows inland from offshore. However, the camanchaca and the stratocumulus clouds lack enough moisture to produce rainfall.