After one of the worst storm disasters in South Africa with so far 443 deaths, President Cyril Ramaphosa declared the nationwide state of emergency.
48 people are still missing, he said in a television speech on Monday.
It is estimated that 40,000 people were displaced by the floods.
"Thousands of people's lives, health and well-being remain at risk," Ramaphosa said.
No electricity and water supply
Heavy rains triggered flooding and mudslides early last week.
In the coastal province of KwaZulu-Natal, about 200 to 400 millimeters of rain fell within 24 hours, Ramaphosa said.
Some areas have neither electricity nor running water.
The Port of Durban, one of Africa's largest cargo ports, is closed until further notice.
Rescue and clean-up squads as well as rescue services are still on duty.
"This is a humanitarian disaster that requires massive and urgent relief efforts," the head of state said.
It is already foreseeable that the economic cost of rebuilding infrastructure and lost production would run into billions of rand (hundreds of millions of euros), Ramaphosa said.
The coastal province of KwaZulu-Natal on the Indian Ocean was already struggling with millions of dollars in damage after days of violent protests and looting in July 2021.
It is one of the most important holiday destinations in the country and had actually already prepared for numerous domestic and foreign tourists.