Braving violent seas and "horrendous" wind, the crew of the salvage tug Smit Amandla narrowly averted a shipping disaster early on Tuesday when they pulled a bulk carrier away from the coast between Slangkop and Llandudno.

The capsized large bulk carrier Kiran, fully laden with iron-ore from Saldanha Bay and full fuel tanks to sail to China, was at one point within six miles of the coast, drifting helplessly without engine power.

Wind of more than 50 knots battered the ship and pushed her through 10-metre swells towards the coast.

"We have put a salvage master and crew aboard the ship and the Smit Amandla was able to tow her to 30 miles off the coast. All seems to be safe now," said Smit Marine spokesperson David Main.

"The ship is in good condition, but it was a close run thing. If she had ended up on the beach, it would not have been a good situation."

The wet and windy weather across the Western Cape is set to get worse, rescue services have warned.

An early warning was sent out yesterday, advising that heavy rainfall - up to 50mm - was expected overnight. Gale force winds were expected to reach 65km/h hour today.

Forecasters predicted the bad weather would persist for the rest of the week, leaving officials fearing flooding in large parts of the Cape Flats where storm-water drainage systems are near-non-existent.

Greg Pillay, head of the city's Disaster Risk Management said this morning that two teams had been dispatched to two informal settlements to assess overnight damage.

"We received reports from Crossroads and Thabo Mbeki (informal settlement) in Philippi and after assessing the damage of the overnight rain, we will determine what relief measures are necessary," he said.

The city had also received reports that Norwood Road in Elsies River and Heerengracht Street in the city centre were flooded earlier today.

Pillay warned that some trees may be uprooted in the expected gale force winds.

Traffic services spokesperson Mogamat Mustapha said there were two incidents of lane flooding - at Table Bay Boulevard and Marine Drive, and at the elevated freeway where the Eastern Boulevard splits. The right-hand lanes had been closed in both instances, and officers were at the scene.

The weather service said a coastal storm was approaching, with rough seas, high waves and big swells expected. NSRI spokesperson Craig Lambinon said there were no incidents at sea since they sent their first weather warnings on Sunday, the worst conditions were expected to hit today and continue tomorrow.

"There will be high swells tonight and tomorrow, so we are asking people to be cautious and as always, we will be on high alert," he said.

The city has urged home owners along the beachfront to prepare for possible "storm surge impacts" to their properties.

The city has also advised people to stay away from the Sea Point Promenade, Atlantic Seaboard, False Bay coastline, and Strand and Gordon's Bay beachfronts.

Pillay said he had seen a worrying trend develop, at the promenade especially, where people thought it was fun to film massive waves crashing around them.

He warned that they were putting their lives at risk.

"They can easily and quickly be swept into the ocean and drown," Pillay said.