Climatic Conditions

CLIMATIC CONDITIONS

The Sahara's climate consists of basically two sub-climates, a dry subtropical climate in the north and a dry tropical climate in the south. The dry tropical climate is generally characterized by mild, dry winters, a hot dry season just before the rainy season, and an annual temperature cycle. Annually high temperature ranges, cold winters, hot summers and two rainy seasons, however, characterize the dry subtropical climate. Winters in the north are cold to cool, in the south, mild. Summers are hot all over the desert. There is a narrow strip in the western portion of the Sahara, along the coast, which generally has cool temperatures compared to the rest of the Sahara because of the influence of the cold ocean currents.

Extreme dryness is one of the Sahara's chief characteristics. Except in a few of the higher mountainous areas, the average annual rainfall nowhere exceeds 5 inches (130 mm). Some areas may have no rain for several years and then receive 5 inches or more. The chief cause of the Sahara's dryness is the northeast trade winds, which blow toward the Equator all year. Daytime temperatures, especially in summer, are among the hottest in the world. Highs of more than 100° F. (38° C.) are common. Because the air is so dry and has so few clouds, the temperature drops quickly after sunset. Differences of as much as 50° F. (28° C.) between day and night occur regularly.