The Horn of Africa is the only semiarid continental region on the Equator. This is strange given that it lies to the west of a warm tropical ocean. The semiarid Horn of Africa marks a discontinuity in the Intertropical Convergence Zone. The affect of upwelling on the lack of precipitation on the Horn of Africa during the summer season is investigated by comparing the modeled precipitation in two climate models, one which accounts for ocean heat transport and one in which it is set to zero everywhere. Other climatic variables are looked at using the NOAA NCEP-NCAR Reanalysis data to examine why the Horn of Africa is so dry. The summer season was emphasized because it is the season with the strongest southerly winds and therefore the strongest case for upwelling.

Model results showed that there is more precipitation on the Horn of Africa and in the eastern Indian Ocean when the ocean heat transport is neglected, thus removing the upwelling of cool waters along the East African coast. Hence coastal upwelling, associated with the southwest summer Asian monsoon may play an important role in the aridity of the Horn of Africa.