Lebanon is in the Near East, to the west of Asia, and its western frontier is the Mediterranean coast. To the north and east, Lebanon borders on semi-desert lands in Syria, and to the south it has a short frontier with Israel.
Lebanon is fairly mountainous. It can be divided into four main structural units from west to east: first, a fairly narrow coastal strip where most of the main towns are located; second, the Lebanon Mountains, a limestone mass reaching above 3,000 metres; thirdly, the Bekaa synclinal depression; and, finally, the Anti-Lebanon Mountains, forming the natural border with Syria. Along the coastal strip there are stepped terraces formed during the Pleistocene rising to 100 metres above sea level. The Lebanon Mountains, which are higher in the north than in the south, reach their maximum height and the maximum for the whole country, at the Qurnat as Sawda (3,088 metres). The Anti-Lebanon Mountains to the east rise to 2,814 metres in their southernmost part. Both ranges are mostly Mesozoic limestone from the Jurassic and Cretaceous because they formed a single system that was split in two when the Great Rift Valley was formed. The sunken part is the Bekaa valley, at altitudes between 800 and 1,200 metres.
Two factors influence the climate of Lebanon: relief and proximity to or distance from the sea. A distinction can therefore be made between the coastal climate, which is fairly moist and warm, with very Mediterranean characteristics; the mountain climate with cold winters and frequent frost; and, further to the east, the arid, dry climate. In Beirut, annual rainfall is 800-900 mm and average temperatures in January and August are 14.4°C and 25.6°C, respectively. The synclinal depression is much drier, with less than 400 mm of rain a year.