Johannesburg - The N3 at Van Reenen's Pass between Harrismith and the Tugela toll plaza was closed for a second time on Tuesday because of snow, the N3 Toll Concession Limited said.
Spokesperson Andy Visser said heavy snowfall in the early afternoon forced authorities to close the road again.
It was briefly reopened just before noon, after being closed in the morning due to the treacherous driving conditions associated with the winter flurry.
Visser said it had snowed along the N3 from Harrismith to Hilton, outside Pietermaritzburg.
Roads closed, reopened
Other roads in KwaZulu-Natal were reopened on Tuesday afternoon, including the N2 between Harding and Kokstad, the R617 between Swartberg Underberg and the P609 Matatiele, Road Traffic Inspectorate spokesperson Zinhle Mngomezulu said.
Earlier, about 200 trucks were held up at Tugela toll plaza. Light motor vehicles had to be diverted towards Newcastle.
Arrive Alive spokesperson Tshepo Machaea said a number of roads in the Eastern Cape had been closed because of significant snowfall.
These included the R61 between Graaff-Reinet and Cradock, the N9 between Graaff-Reinet and Middelburg, the R58 in the region of Barkly East, and the R68 between Barkly East and Lady Grey.
Machaea appealed to motorists to respect the rules of the road and to exercise extreme caution.
Airports Company SA spokesperson Unathi Batyashe-Fillis said there had been snow at OR Tambo International Airport, but that it had not been heavy enough to affect flights by midday.
"There is currently no word that flights have been reduced, but each airline makes their own call on this."
In the Free State, the Golden Gate Highlands National Park, operated by SA National Parks, had its heaviest snowfalls in six years. Hotel manager Gerrit Potgieter described the snow as "really thick" and said more was falling.
On social networks, South Africans posted photographs and text updates of snow around the country. In Johannesburg's CBD, people flocked onto the streets to see the snowflakes whirling between the tall buildings.
Disaster management teams on standby
The KwaZulu-Natal co-operative governance and traditional affairs department said it had placed its disaster management teams on standby.
"Emergency rescue and disaster personnel have been dispatched to various parts of the province, especially the interior, where heavy snow is currently falling and making the N3 impassable," spokesperson Vernon Mchunu said.
Co-operative governance and traditional affairs MEC Nomusa Dube said no disastrous situations had been reported.
"The cold weather is set to continue throughout the day and into the night, and so is the rainfall.
"Therefore, we urge communities to be cautious with fires as they try to heat up their homes to keep warm," Dube said.
She also urged motorists to drive carefully, as the roads were slippery and snowfalls were forecast in some parts of the province.
SA Weather Service forecaster Jan Vermeulen said there would be a brief reprieve from the freezing conditions from Wednesday, but on Friday another cold front would hit the country from the south west, bringing a fresh wave of icy weather.