Strong winds and heavy rain have downed trees, damaged properties and flooded roads as a complex weather system rages along Australia’s east coast.

The first flood warnings were issued for metropolitan Sydney on Wednesday as the deluge continued.

Emergency crews had a busy workload overnight, with seven flood rescues on the NSW south coast, all caused by people driving into floodwaters.

About 200 properties in Burrill Lake on the NSW south coast were flooded overnight, while more than 200 millimetres of rain smashed several towns, including Morton and Ulladulla.

The NSW State Emergency Service received more than 2300 calls for help in the 24 hours to 9.30am.

“It was indeed a very wild night for many people across the east coast of NSW,” Deputy Commissioner Debbie Platz said.

“We are very grateful the communities in these areas heeded our warnings, that has meant that there has not been as much damage to property and impact to lives as what could have been, but we did see conditions deteriorate overnight.”

At Moss Vale, in the NSW southern highlands, a 55-year-old man was taken to hospital with serious head and torso injuries after a tree fell and crushed his truck .

Police, paramedics and emergency crews extracted the unconscious man from the driver’s cabin of his truck at 10.30pm on Tuesday.

Communities stretching from Queensland’s Lockyer Valley to Bega on NSW’s south coast are still being warned to take care as severe weather driven by a “vigorous” coastal low lingers offshore.

The storm, called a cyclone bomb, was expected to track south on Wednesday before turning back out into the Tasman Sea on Thursday.

Peak waves hit about 12 metres off the NSW south coast on Wednesday, after 10 metres off Sydney on Tuesday.

By midday Wednesday, 34 warnings were current, with 335 properties on the central and south coasts subject to evacuation or shelter now warnings.

• See all NSW warnings here

Shortly after midday, advice-level flood warnings were issued for Camden in Sydney’s south-west, as well as Penrith and North Richmond in the west.

The rising Nepean River is the main concern in Camden and Penrith, while in North Richmond the focus is the Hawkesbury River.

Sydney’s Warragamba Dam is expected to spill in coming days, although it was yet to reach capacity on Wednesday.

SES crews had responded to more than 2320 incidents by early Wednesday morning, as the low shifted southwards from Newcastle toward Sydney, the Illawarra and South Coast.

More than 37,000 homes and business were without power and many flights were cancelled from Sydney Airport for the second consecutive day.

Residents were being warned to evacuate amid coastal erosion on the Central Coast. Dunleith Tourist Park manager Ryan Lloyd said the beaches had been hit hard as wind gusts and swells intensified.

“It’s pretty wild – pretty full on – a bit scary for the home-owners too,” he said.

There were patches of blue in the sky but they were otherwise surrounded by dark clouds.

But the rain was less of a concern than the strong winds.

“We’ve already had plenty of tree branches down … they’re dropping limbs everywhere,” Lloyd said.

“It’s just battening down now, just wait for it to blow over – pardon the pun – then a massive clean-up for the next couple of days.”

The rain was expected to begin to ease late on Wednesday. The Bureau of Meteorology predicts another low-pressure system will enter the storm’s path about then.

“We see another low-pressure system, really dumb-belling around that first one, that will really intensify and reinforce some of those winds and rain across the south coast,” senior meteorologist Jonathan How said.

The system extends about five kilometres into the sky, with two low-pressure systems interacting with one another in a phenomenon known to meteorologists as the Fujiwhara effect.

-with AAP