Horn of Africa periodic monsoon winds and irregular rainfall. Mean daily maximum temperatures range from , except at higher elevations along the eastern seaboard, where the effects of a cold offshore current can be felt. Somalia has only two permanent rivers, the Jubba and the Shabele, both of which begin in the Ethiopian Highlands. About 220 mammals are found in the Horn of Africa. Among threatened species of the region, there are several antelopes such as the beira, the dibatag, the silver dikdik and the Speke's gazelle. Other remarkable species include the Somali wild ass, the desert warthog, the hamadryas baboon, the Somali
Horn of Africa single landmass around 18 million years ago, before the Gulf of Aden rifted and separated the Horn region from the Arabian Peninsula. The Somali Plate is bounded on the west by the East African Rift, which stretches south from the triple junction in the Afar Depression, and an undersea continuation of the rift extending southward offshore. The northern boundary is the Aden Ridge along the coast of Saudi Arabia. The eastern boundary is the Central Indian Ridge, the northern portion of which is also known as the Carlsberg Ridge. The southern boundary is the Southwest Indian Ridge. Extensive glaciers once