Gale force winds plunged parts of Sydney into darkness and kept emergency services busy with about 730 calls for help, mainly from people with roofs damaged by large fallen trees.
Wind gusts of up to 100 kilometres an hour hit the city in the afternoon, knocking over hundreds of trees and damaging rooftops.
The State Emergency Service (SES) says it received abound 730 calls for help, however the ambulance service says no-one has been seriously injured.
One woman in Punchbowl has been treated for lacerations after a tree fell on her head and a temporary wall fell injuring a man's leg in Cronulla.
More than eight thousand homes and businesses remained without power in Sydney and the surrounding regions, and power was cut around the Broadway and Ultimo areas of inner Sydney, plunging the area into darkness and affecting traffic lights.
Ausgrid says a burst water main in Ultimo caused the power supply problems, and crews were expected to take several hours to fix the problem.
Earlier, there was a severe weather warning from the Hunter to the Illawarra and out to the Central Tablelands and Snowy Mountains as a vigorous cold front moved through.
The SES's Danielle Wearne said emergency crews would be working through the night to get through the backlog of calls.
"It's very possible that we won't finish them all overnight, so we've got all our crews and volunteers out working throughout the night and they'll be getting through as many jobs as they can but we are expecting that these jobs will be carried over to tomorrow," she said.
She says one home in Epping has been badly damaged.
"A carport has been detached from a house and has landed on a roof and knocked a chimney over and caused considerable roof damage to that property." Meanwhile, 10 people were rescued from the water after several boats overturned and washed ashore along the coast.
The Westpac helicopter retrieved a kayaker who was swept two kilometres out to sea off North Avoca on the central coast.
A further two people were pulled from the water near Culburra on the south coast, when their boat capsized near the mouth of the Crookhaven River.
Stephen Leahy from the Westpac Rescue Helicopter says another seven people were saved at North Cronulla.
"Reports had been received there that a boat had overturned in the high winds there, with up to five people in the water.
Local lifeguards quickly rescued all of those people," he said.
"But as the helicopter arrived we then found another boat which had overturned and had engine trouble.
Everyone was safe and well with that." The weather bureau said the winds were expected to ease overnight.