The statement came as new figures released by the Integrated Phase Classification (IPC), the internationally recognised famine early-warning system, showed that 2.1 million children aged under five would be suffering from acute malnutrition by June 2025, an increase of 27 per cent from 1.65 million, Xinhua news agency reported.
"This includes more than 650,000 children expected to be facing the most deadly form of malnutrition - severe acute malnutrition - a rise of 30 per cent from 480,000," Save the Children said in a statement.
The charity noted that the spillover impacts of war in Sudan also added to a worsening hunger crisis and called for international funds to scale up aid.
According to Famari Barro, interim country director for Save the Children in South Sudan, large swathes of South Sudan are currently underwater as heavy downpours cause massive floods, displacing families and children.
"Earlier this year, schools were closed across the country as scorching temperatures of up to 45 degrees Celsius threatened the lives of millions of school-going children. Today, the same children are reeling from devastating floods with no end in sight to these climate shocks," he said.
The charity called for urgent action to stop the impact of back-to-back devastating extreme weather events crushing the lives of children.
"There also needs to be an urgent injection of international funds to scale up humanitarian aid to address the major driving factors of acute malnutrition including improving the quality of diet consumed by children, improved access to safe water and sanitation services, prevention, and treatment of childhood illnesses," Barro added.
According to the IPC report, the hunger situation is worsening in South Sudan, with nearly half of the population, or 6.3 million people, facing acute food shortages, compared to 5.8 million over the September-November period last year.
"With current widespread flooding and ongoing conflict, the number of people facing acute food shortages is expected to increase to 7.7 million by July next year," Save the Children said.