The latest outlook confirms the fears of aid agencies which have been warning for months about the worsening consequences of the drought for Ethiopia, Somalia and parts of Kenya, including a risk of famine for Somalia.
"Sadly, our models show with a high degree of confidence that we are entering the 5th consecutive failed rainy season in the Horn of Africa," said Guleid Artan, Director of the IGAD Climate Prediction and Applications Centre (ICPAC), WMO’s regional climate centre for East Africa.
"In Ethiopia, Kenya, and Somalia, we are on the brink of an unprecedented humanitarian catastrophe," he added.
The World Bank said in June that an estimated 66.4 million people in the Horn of Africa region were forecast to experience food stress or a food crisis, emergency, or famine by July. New estimates based on the latest forecasts were not immediately available.
The drought has coincided with a global rise in food and fuel prices, pushed up by the war in Ukraine, that has hit parts of Africa hardest.
"The WHO is very concerned about this situation. It does lead to many families taking desperate measures to survive," said Carla Drysdale, a spokesperson for the World Health Organization told a Geneva press briefing.