eThekwini Municipality said its disaster management centre and emergency services are on high alert, following a Level 6 warning against disruptive rain, forecast from Thursday.
Rains on Tuesday led to flooding on the N3 Eastbound near the Tollgate Bridge, which was cleared later on the same day.
The South African Weather Service (SAWS) forecast intense rainfall along the south coast and adjacent interior of KwaZulu-Natal until Friday.
Similar yet lesser conditions (at Level 4) are expected over the eastern and northern Free State, north-western KwaZulu-Natal, and the southern Highveld of Mpumalanga.
Disruptive rain (Level 2) is also forecast over the eastern parts of the Eastern Cape, the southern parts of the Northern Cape and the northern parts of the Western Cape.