Mediterranean climates, opposite to the humid subtropical and monsoonal climates, have a dry summer, with rainfall in the winter and cooler months. They occur mostly at the western edges and coasts of the continents and are bounded by arid deserts on their equatorward sides that cause the dry season of summer, and oceanic climates to the poleward sides that are influenced by cool ocean currents and air masses that bring the rainfall of winter. The five main Mediterranean regions of the world are the Mediterranean Basin in northwestern Afro-Eurasia, coastal California in the United States, the southwest of Australia, the Western Cape of South Africa and the south and southwestern coast of Chile.