Violent downpours in October have displaced tens of thousands in Somalia, submerged whole towns in South Sudan and killed dozens in flash floods and landslides in Kenya, Ethiopia and Tanzania.
More than one million people in East Africa have been affected by flooding after higher than normal rainfall, an aid group said on Friday. Parts of the region are bracing for a tropical storm, Kyarr, that could worsen an already dire humanitarian situation.
The International Rescue Committee said many people had been reeling from an earlier period of severe drought. Now the rains in parts of Somalia, South Sudan and Kenya are expected for another four to six weeks.
"This further damage to life and livelihood is likely to have long-lasting consequences on the most vulnerable who are only just getting back on their feet," said Kurt Tjossem with the IRC.
The flooding in Somalia, which has caused several deaths, has displaced more than 180,000 people and destroyed crops, the aid group Action Against Hunger said. It estimated that the tropical storm would bring another metre of water to parts of the region.
"For many people, this is the worst flooding in a lifetime," the group's regional director Hajir Maalim said, adding that food is no longer reaching many people with roads and bridges submerged.
South Sudan President Salva Kiir earlier this week declared a state of emergency in 27 counties because of the flooding.
The United Nations has said entire communities in some areas have been submerged, disease is spreading and access to health services is limited.
People in many of the areas already faced acute malnutrition as South Sudan emerges from a five-year civil war.
"I am extremely concerned about the humanitarian consequences of the floods," said Alain Noudehou, the UN's humanitarian coordinator in the country.
Experts called the floods a worrying sign of how climate change is affecting already vulnerable communities.
"The floods are getting worse and they're happening more frequently," said Nhial Tiitmamer, director of the environmental and natural resources program at the Sudd Institute, a South Sudanese think tank.
The floods there are the heaviest in six years in terms of the depth and the extent of the area affected, he said.