City officials said the fire in the Simonstown area was spreading fast and had led to various homes being evacuated, including 20 residents from a retirement home.
"There are road closures currently in Dido Valley and Main road and in Glen and Main roads in Simonstown. Residents are requested that if they are entering or leaving Simonstown to go via Cape Point," Disaster risk management spokeswoman Mandy Thomas said.
Thomas said visibility was low in the area due to smoke.
She advised residents with respiratory problems to stay away from the area.
"At this stage all city services are responding to the fire – safety and security services as well as the NSRI [National Sea Rescue Institute], DRM volunteers and the Cape Medical response."
Fires were also affecting the areas of Glencairn, Da Gama Park and Kommetjie.
Firefighters were also still on scene in Somerset West where a fire in the Helderberg mountains, which last week destroyed almost half of the historic Vergelegen farm and caused extensive damage to the Bezweni Lodge in Sir Lowry's Pass Village, had been contained.
Two helicopters had been assisting ground crews with damping down operations.