The Sahelian Zone extends south of the Saharan Zone to within approximately thirty kilometers of the Senegal River. It forms an east-west belt with its axis running from Boutilimit through 'Ayoûn el 'Atroûs to Néma, made up of steppes and savanna grasslands. Herds of cattle, sheep, and goats move across this zone in search of pasturage.

The hivernage begins earlier in the Sahelian Zone than in the Saharan Zone, often lasting from June until October. Because farmers and herders depend on annual rains, a delay of one month in the beginning of the rainy season can cause large losses and lead to mass migrations from Hodh ech Chargui and Hodh el Gharbi into Mali. Although temperature extremes are narrower than in the Saharan Zone, daily variations range from 16° C to 21° C. The harmattan is the prevailing wind.

In the northern Sahel, dunes are covered with scrub grasses and spiny acacia trees. Farther south, greater rainfall permits more dense vegetation. Sands begin to give way to clay. Large date palm plantations are found on the Tagant Plateau, and savanna grasses, brushwood, balsam, and spurge cover fixed dunes. Occasional baobab trees dot the flat savanna grasslands of the southern Sahel. Forest areas contain palm trees and baobabs. Vast forests of gum-bearing acacia grow in Trarza and Brakna regions. Farther south, particularly in Assâba and the northern portion of Guidimaka regions, rainfall is high enough to support forms of sedentary agriculture.

Data as of June 1988