Portugal is defined as a Mediterranean climate (Csa in the South, interior, and Douro region; Csb in the North, Central Portugal and coastal Alentejo; mixed oceanic climate along the northern half of the coastline and also Semi-arid climate or Steppe climate (BSk in certain parts of Beja district far South) according to the Köppen-Geiger Climate Classification), and is one of the warmest European countries: the annual average temperature in mainland Portugal varies from 8–12 °C (46.4–53.6 °F) in the mountainous interior north to 16–19 °C (60.8–66.2 °F) in the south and on the Guadiana river basin. The Algarve, separated from the Alentejo region by mountains reaching up to 900 metres (3,000 ft) in Alto de Fóia, has a climate similar to that of the southern coastal areas of Spain or Southwest Australia.