Source: The Library Of Congress Country Studies
The Jabal an Nusayriyah mountains, a range paralleling the coastal plain, average just over 1,212 meters; the highest peak, Nabi Yunis, is about 1,575 meters. The western slopes catch moisture-laden western sea winds and are thus more fertile and more heavily populated than the eastern slopes, which receive only hot, dry winds blowing across the desert.
Inland and farther south, the Anti-Lebanon Mountains rise to peaks of over 2,700 meters on the Syrian-Lebanese frontier and spread in spurs eastward toward the plateau region. The eastern slopes have little rainfall and vegetation and merge eventually with the desert.
In the southwest, the lofty Mount Hermon (Jabal ash Shaykh), also on the border between Syria and Lebanon, descends to the Hawran Plateau-- frequently referred to as the Hawran--that receives rain-bearing winds from the Mediterranean.
The most striking feature of the climate is the contrast of sea and desert. Between the humid Mediterranean coast and the arid desert regions lies a semiarid steppe zone extending across three-fourths of the country and bordered on the west by the Anti-Lebanon Mountains and the Jabal an Nusayriyah, on the north by the Turkish mountain region, and on the southeast by the Jabal al Arab, Jabal ar Ruwaq, Jabal Abu Rujmayn, and the Jabal Bishri ranges.
Rainfall in this area is fairly abundant, annual precipitation ranging between 75 and 100 centimeters. Most of the rain, carried by winds from the Mediterranean, falls between November and May. The annual mean temperatures range from 7.2° C in January to 26.6° C in August. Because the high ridges of the Jabal an Nusayriyah catch most of the rains from the Mediterranean, the Al Ghab depression, located east of these mountains, is in a relatively arid zone with warm, dry winds and scanty rainfall. Frost is unknown in any season, although the peaks of the Jabal an Nusayriyah are sometimes snow covered.
Farther south, rain-bearing clouds from the Mediterranean pass through the gap between the Jabal an Nusayriyah and the Anti-Lebanon Mountains, reaching the area of Homs and, sometimes, the steppe region east of that city. Still farther to the south, however, the Anti-Lebanon Mountains bar the rains from the Mediterranean, and the area, including the capital city of Damascus, becomes part of the semiarid climatic zone of the steppe, with precipitation averaging less than 20 centimeters a year and with temperatures from 4.4° C in January to 37.7° C in July and August. The vicinity of the capital is, nevertheless, verdant and cultivable because of irrigation from the Barada River by aqueducts built during Roman times.
In the southeast, the humidity decreases, and annual precipitation falls below 10 centimeters. The scanty amounts of rain, moreover, are highly variable from year to year, causing periodic droughts. In the barren stony desert south of the Jabal ar Ruwaq, Jabal Abu Rujmayn, and Jabal Bishri ranges, temperatures in July often exceed 43.3° C. Sandstorms, common during February and May, damage vegetation and prevent grazing. North of the desert ranges and east of the Al Ghab depression lie the vast steppes of the plateau, where cloudless skies and high daytime temperatures prevail during the summer, but frosts, at times severe, are common from November to March. Precipitation averages 25 centimeters a year but falls below 20 centimeters in a large belt along the southern desert area. In this belt, only the Euphrates and Khabur rivers provide sufficient water for settlement and cultivation.
Data as of 1987