Catastrophe declared after Sydney storm

The Insurance Council of Australia has declared a catastrophe after the freak storm that's left a trail of destruction in Sydney's south.

The suburb of Kurnell was hit hardest as winds reached 213km/h on Wednesday morning, causing damage to homes, businesses, cars and infrastructure.

By 9.30am on Thursday, insurers had received about 1000 claims with losses estimated at $8 million, the ICA said.

CEO Rob Whelan said the catastrophe declaration allows insurers access to the industry's disaster response resources.

"The ICA and its members are liaising with the NSW government, agencies and the emergency services in response to the damage caused," Mr Whelan said.