Heavy floods and drought sparked by the El Nino weather phenomenon in East Africa in coming weeks could see the number of people needing aid soar by over 80 percent, the UN warned Friday.

El Nino is sparked by a warming in sea surface temperatures in the equatorial Pacific, setting off changing weather patterns across the world, and can cause unusually heavy rains in some areas, and drought elsewhere.

"The number of food insecure people in the region is expected to increase by 83 per cent, from approximately 12 million people at the start of 2015, to 22.1 million people by the start of 2016," the UN Office for the Coordination of Humanitarian Affairs (OCHA) said in a report Friday.

"In addition, between 2.7 million and 3.5 million people could be affected by floods," the report added, focusing on 10 nations across East Africa and the Horn of Africa.

The El Nino phenomenon, a global weather pattern known to wreak havoc every few years, is expected to last until early 2016.

While some countries -- including Sudan, Eritrea, Ethiopia and Djibouti -- could see drier conditions, other countries including Kenya, Somalia and Uganda could see floods.

The UN said that government and aid workers are "racing against the clock to prepare for floods caused by El Nino," and have appealed for $451 million (409 million euros).

Ethiopia is an especial concern, with the number needing food aid rising from 2.9 million at the beginning of 2015 to 8.2 million today, with some 15 million people likely to need aid by early next year, the UN said.

East Africa was struck by intense drought in 2011, the worst in 60 years, with some 12 million people in four nations affected.

Parts of Somalia were declared famine zones, and more than 250,000 people died, half of them children.

South Sudan, where fighting continues in its 22-month long civil war, is also likely to be affected. The UN warned on Thursday that over 30,000 people there are already starving to death, and that tens of thousands more are on the brink of famine.

"Severe and moderate acute malnutrition among children has significantly increased in Ethiopia, Somalia, and South Sudan," the OCHA report read.