Parts of Northern Natal, Zululand and the northern provinces, Limpopo and Mpumalanga, have received very heavy downpours in recent days, with more rain expected on Wednesday and Thursday.
According to SAWS figures disseminated on social media, more than 60mm fell in 24 hours in Mtunzini, 81mm was recorded in the 24 hours ending 8am on February 20, and 50mm was recorded at Richards Bay airport.
Isimangaliso Wetland Park posted images on social media indicating the impact of the rain, while the Hluhluwe Dam was shown overflowing at 101%.
Kosi Bay and Riverview also saw significant rain.
Limpopo was inundated, with one area - Tshivhase Tea Estate - catching 195mm in 24 hours, according to SAWS figures.
Videos showed the Limpopo River in flood impacting on access to Beitbridge border post.
There are more scattered thunderstorms expected in the north-east of the country on Wednesday, including parts of Northern Natal and Zululand.