The climate models that simulate the current climate most realistically do not show a coherent picture for this region. Most models simulate drier conditions during the 21st century in eastern Sudan and Ethiopia. This drying has been prevalent during the last decades of the 20th century in these regions. There is little consensus among the models with respect to their simulated changes in extreme rainfall events. A spatially coherent pattern is the increase in 10-year highest rainfall events over northern Somali and the Horn of Africa, and more severe dry events over the same areas. Thus extreme events are likely to become more intense over much of North-east Africa, particularly over the east.

Observational climatology based on the 1971-2000 period calculated from the Climate Research Unit (CRU) data set TS 2.1 show a clear precipitation maxima between 35° and 40° E over the Ethiopian highlands region. A relative minima is located in Eastern Sudan. There appear to be another minima in Somali, Djibouti and Eritrea but this is an artifact of lack of gauge observations in these areas, from which the CRU data are constructed.

A preponderance of the evidence from the model predictions support an increase in the intensity of 10-year highest rainfall events in the Greater Horn of Africa. Over Ethiopia and eastern Sudan the uncertainty is larger as the models behave differently with respect to their simulated changes in wet extremes. It is of interest to note that despite the predicted downward trends in long-term rainfall means, the intensity of heavy rainfall events is predicted to rise over the Horn.

Over the same areas where the models predict more intense wet extremes (in the Greater Horn of Africa), indications are for more severe dry conditions as well in future climate. The implication therefore is that in these areas the rainfall distribution is getting more broader in future climate.