Most of Morocco north of the Western Sahara, particularly along the coasts, experiences a typical Mediterranean climate, with mild wet winters and hot dry summers. The rainy season generally extends from October to April. Torrential downpours occasionally produce devastating floods, but overall several factors act to reduce the country’s rainfall. Morocco is on the southern margins of the mid-latitude tract of frontal storm systems that regularly traverse the North Atlantic. As a result, rainfall levels are relatively low and gradually decrease from north to south. High-pressure ridges, moreover, periodically develop offshore during the rainy season, shifting storms to the north. Drought results when these ridges persist for extended periods. The cold Canary Current off the western shores also induces atmospheric stability and further decreases the potential for precipitation.

In the broad coastal lowlands, average annual precipitation diminishes progressively from about 32 inches (800 mm) on the northern Gharb plain to less than 8 inches (200 mm) in the Sous valley. Farther south, beyond the Anti-Atlas, semiarid conditions quickly fade into desert. Elevation strongly influences this prevailing pattern, however, with significantly greater amounts of precipitation occurring in the mountains. The central Rif, for example, receives more than 80 inches (2,030 mm) of precipitation annually, and even the High Atlas, much farther south, receives some 30 inches (760 mm). Snow is common at approximately 6,500 feet (2,000 metres), and the snowpack lingers in the highest elevations until late spring or early summer. Morocco’s mountains create a significant rain shadow, directly east of the mountains, where in the lee of the prevailing winds, desert conditions begin abruptly.

In the lowlands near the coast, summer heat is reduced by cool onshore breezes. Average daily summer temperatures in the coastal cities range from 64 to 82 °F (18 to 28 °C). In the interior, however, daily highs frequently exceed 95 °F (35 °C). In late spring or summer, the sharqī (chergui)—a hot, dusty wind from the Sahara—can sweep over the mountains into the lowlands, even penetrating the coastal cities. Temperatures rise dramatically, often reaching 105 °F (41 °C). If crops have not been harvested, damage can be extensive from the desiccating effects of the sharqī. In winter, the marine influence again moderates temperatures in the coastal regions. Average daily winter temperatures range from 46 to 63 °F (8 to 17 °C). Away from the coast, temperatures drop significantly, occasionally dipping below the freezing point.