The heating of the West African land mass during the Northern Hemisphere summer creates much hotter and dryer conditions in central West Africa than immediately south in the ITCZ.

A jet develops due to the significant surface temperature and moisture gradient from the Gulf of Guinea to the Sahara.

From August to September, the mature phase of the West African Monsoon, the African Easterly Jet reaches maximum mean wind speeds of approximately 13 m/s. The jet maximizes at a height of about 4 km (or 650 hPa) and typically around 11°N latitude.