Cars, buses and trucks became stuck in heavy snow on Friday in the east of the country with the key N3 route linking Johannesburg and the east coast city of Durban one of the roads most severely affected.

A 39-year-old woman died from hypothermia in hospital on Saturday after spending Friday night with other passengers in a minibus taxi stranded by the weather, Midlands EMS emergency services operations manager Roland Robertson told AFP.

The travellers had been stopped near the town of Mooiplaas about 430 kilometres (270 miles) from Johannesburg.

"They were exposed to the cold and everything the whole night, with no blankets, no anything. They weren't prepared for what happened," Robertson told the ENCA broadcaster. "Unfortunately she did demise at the hospital later."

While some inland areas of South Africa often receive dustings of snow during their winter, heavy snow falls are rare. Unconfirmed media reports spoke of two metres falling in some areas.

Recovery operations were continuing under extremely challenging conditions Sunday with a backlog around Van Reenen's Pass in the Drakensberg mountains, about 330 kilometres southeast of Johannesburg, said the N3 Toll Concession which manages the route.

Cars were being escorted out of the area but abandoned and broken-down vehicles, some of which were four abreast, were making it difficult for road graders to clear the snow and for search and rescue teams to reach people still stranded, operations manager Thania Dhoogra said.

"The latest report we have is that there is an approximately 30-kilometre backlog of traffic that's currently impenetrable," she told ENCA news.

The authorities have not yet been able to say how many people or vehicles were in total stranded on the roads by the snow.