The Bureau of Meteorology predicts continued rain and strong winds will sweep across New South Wales into the weekend, with Sydney on the "southern edge" of stormy weather.

Senior meteorologist Angus Hines said Sydney's weather could change from stormy to a "dreary" mix of wind, rain and cloud. He said it would be "persistent winds" and "quite cold".

He said while the severe storm that hit Sydney on Wednesday had developed in Victoria and moved eastwards, a low pressure system in the Tasman Sea would now bring strong winds and rain to the east coast of New South Wales.

The same weather system is expected to affect parts of eastern Victoria and southeast Queensland. The bureau has warned of damaging winds, hail and heavy rainfall for parts of the Gold Coast.

Mr Hynes said eastern New South Wales, particularly the northern rivers region, was at the highest risk of severe thunderstorms on Thursday, with more heavy rain, damaging winds and the possibility of large hail expected.

Heavy rainfall and damaging winds are also possible in the Hunter and mid-north coast over the next 48 hours.

On the other side of the country, Western Australia faces the highest risk from tropical cyclones so far this season, Hines said.

"The most likely impact is heavy rainfall around the Pilbara and northern Western Australia, and particularly strong winds off the Pilbara coast." He said there could be very large waves along the northern WA coastline.

Elsewhere, very hot weather will continue in northeast Queensland, with a severe heatwave expected from Bundaberg to north of Cairns in the coming days, he added.

"Temperatures are four to eight degrees warmer than normal in many areas for this time of year," he said.

He said Wednesday's thunderstorms caused 1.2 million lightning strikes, with damaging wind gusts exceeding 100 kilometers per hour in many areas and heavy rains. "It's very dramatic.

"Nearly everyone from Melbourne to Sydney and everything in between, including all of Canberra, will have a taste of it... when that storm rolls through."

Wind gusts were as high as 107 km/h at Sydney Airport, 109 km/h at Newcastle Airport and 120 km/h at Williamtown Airport.

While most rainfall totals were between 20mm and 40mm, Eurobodalla on the NSW south coast received 127mm.

The weather caused severe damage and widespread power outages.

More than 143,000 homes and businesses in New South Wales were without power, with about 90 per cent caused by lightning strikes, according to Ausgrid. Sydney's north, Hunter and Newcastle areas were worst hit.

Australia Grid said crews were working through the night to restore power to 50,000 homes and businesses. They are focused on restoring power to remaining customers as quickly as possible.

The State Emergency Service received more than 2,250 calls and responded to 1,800 incidents.

A man in his 80s has died after a tree fell on his vehicle in Cowra, the SES said.

According to the BoM, Australia's surface temperatures have increased by 1.5 degrees Celsius since 1910, leading to longer and more intense heatwaves. The climate crisis is also leading to an increase in the number of extremely hot days.