The Cape Verde islands have a generally hot
semi-arid climate, with rainfall mostly limited to the months August and September. The driest areas are the low eastern islands (
Maio,
Sal and
Boa Vista), and the southwestern parts of the more mountainous islands. The higher and northeastern,
windward parts receive more precipitation. Agriculture strongly depends on the summer rains, which are highly variable; in years with less rain, crop failure was common. In addition, rains tend to come in a few large events in which most water runs off into the ocean, creating erosion rather than replenishing the water table. The situation was further aggravated by unsuitable crop choice, overpopulation,
overgrazing and inadequate response from the Portuguese colonial administration. Portuguese colonial policy favored the establishment of
morgados, large landed estates handed down to a single heir. This left much of Cape Verde's population renting or sharecropping, with little incentive to improve their lands for better drought resistance. The
colonial administration also promoted cash crops such as
coffee,
sugar, and
cotton in irrigated lands rather than food crops. Corn was and is the primary grain grown. It requires far more rain than Cabo Verde usually receives, but the cultural norms established during Portuguese rule prioritized this familiar crop over more ecologically appropriate and drought-resistant
millet and
sorghum varieties common in West Africa. ==Historical famines==