The authorities on Tuesday declared a code red emergency in the picture-perfect region between Franschhoek and Paarl, the crucible of South Africa's wine industry.
Emergency services struggled to put out a series of blazes, deploying four helicopters, 13 vehicles and 120 firefighters.
"The fire is not under control at the moment," said Liesl Brink, incident command spokesperson for the fire fighting effort.
Separate blazes raged on mountains near both towns, while several smaller fires smouldered, sending dense smoke over the area and obscuring the mountains which draw tourists to the area in droves.
A total of 7 100 hectares of land – including farmlands – alien vegetation and indigenous fynbos have already been destroyed.
Two workers' cottages were burned down and two farms had to be temporarily evacuated.
No deaths have been reported, but a warning has been issued to residents to be alert.
Firefighters were battling difficult conditions to put out the flames, Brink said.
"There is quite a strong wind out here, the wind's blowing at 40 kilometres per hour, it's also very hot, temperatures are soaring above 30 degrees [Celsius],"she said.
The cause of the blaze is still unknown.
But according to Brink, many fires at this time of year – when wind and hot summer months provide "perfect conditions for runaway fires" – had been shown to be caused by people, often children.
The fire started on Sunday in Franschhoek, about an hour's drive from Cape Town, and was moving towards nearby Paarl which lies slightly to the north-west.
Choppers laden with water bombs circled the area on Tuesday, dropping their payload before rushing back to a make-shift control centre at the prison where democracy hero Nelson Mandela walked free from 27 years of apartheid jail.
On the ground, the livelihoods of scores of farmers hung in balance.
Trees at the Freedom Hill winery burned near the tasting room and smoke from the nearby fires hovered menacingly over the vines.
The winery has 18 hectares of cabernet, shiraz and pinotage grapes that are due to be harvested within weeks.
So far the owners have been relatively lucky, losing less than a hectare of merlot grapes which are no longer used for wine.
But the path of the blaze is unpredictable.
Possibility it might return
"We are very worried that it would come back," said tasting room manager Malisha Fortuin.
With blackened vegetation a stone's throw away, workers on a fruit farm were busy harvesting plums while a chopper flying above was water bombing a nearby fire.
"I'm not scared of fire. I have worked with fire a few times," said worker Lionel Plaatjies.
Back-up teams have been called in from the city of Cape Town and other provinces.
"The fire has been declared a code red meaning that we've used all of our available resources and are pulling all the resources that we can," Brink said. – Sapa-AFP