Strong winds are hampering efforts to fight a fire in the Du Toitskloof Pass area near Paarl, the Cape Winelands District Municipality said on Friday afternoon.
Spokesperson Jo-Anne Otto said the municipality was focusing on bringing the fire under control and protecting farms.
Cape Nature and the Fire Protection Association were working closely with landowners to prevent property damage.
The fire, which broke out on Tuesday, has burnt about 3500ha of mixed fynbos.
"There is grave concern that the wind, which is expected to pick up during the night, will cause flare-ups in areas previously beaten down. Active firefighting will continue throughout the night."
No evacuation orders have been issued and the Huguenot tunnel was still open to traffic.