Rescue workers evacuated over 2,000 people and dozens of trucks were stranded as heavy rains and snow battered southern parts of South Africa over a freezing weekend, officials said.

The precipitation had cut off all road links between economic hubs Johannesburg and Cape Town, causing a huge traffic backlog, though main highways linking the north and south of the country were reopened Sunday afternoon, said Road Traffic Management Corporation spokesman Ashraf Ismail.

Dozens of trucks had been stuck on the routes after heavy snow had closed them down since Saturday.

Soon after traffic was opened, around 500 trucks that had been held up in Johannesburg by the closures started the trek toward Cape Town in the south, Ismail told AFP.

Over 100 millimetres (four inches) of rain fell over the area in three days, with more heavy showers predicted through Sunday night.

Thousands of people were moved to community centres as floods hit southern city Port Elizabeth, said municipal spokesman Kupido Barron.

"We assisted more than 2,000 people," he told AFP, with mattresses, soup and blankets given to families housed in community centres.

Police were also looking for two people who ignored a ban and rowed across a flooded road in an inflatable rubber boat, local media reported.