Climatic zones range from the subtropical deserts in the north to the temperate rain forests of Aisén and the tundras of Magallanes in the extreme south. The cold Humboldt Current, traveling northward from the Antarctic, affects the climate of the coastal regions of central and northern Chile. Generally, however, Chile is divided into three climatic regions: (1) The north, which contains the Atacama Desert, one of the driest regions in the world, is characterized by hot and arid weather in the lowlands and occasional summer showers in the Andean highlands. (2) The middle, extending about 1,450 km (900 mi) from 30°to 43° S , has a Mediterranean climate, with mild, wet winters, averaging 11° C (52° F ), and long, dry summers, averaging 18° C (64° F ). (3) The south, a region of mountains and fjords, has high winds and heavy rains. Annual rainfall ranges from no recorded precipitation in some parts of the north to 50–100 cm (20–40 in) around Concepción, in south-central Chile, to more than 406 cm (160 in) in some southern regions. South of the Bío-Bío River, rains occur all year round. The Andean highlands, even in the tropical north, are cold and snowy.