The Famine Early Warning Systems Network says more than one-million people in south and southeast Ethiopia face "extreme food insecurity" due to the failure of normal late-year rains.
The U.S.-funded group says pre-famine conditions have emerged in several districts, including Afder, Liban and Gode).
The group says two million people need humanitarian aid in Somalia, mostly in the south, where the poor rainfall has led to widespread crop failure. It also warns of a food crisis in northern Kenya.
It says food aid has been dispatched to the affected regions but that the crisis will likely intensify during the dry season in early 2006.
The United Nations issued humanitarian appeals this month for Somalia and Kenya.