A man has been critically injured by a falling tree as a wild storm hit Orange in the NSW central tablelands on a third straight day of dangerous supercell storms.

The weather bureau issued a severe thunderstorm warning for greater Newcastle and parts of the Blue Mountains on Wednesday, covering about 250 kilometres from the outskirts of Nowra to Wyong on the NSW central coast.

Further south, the weather bureau has also issued a “stay indoors” warning for parts of the Victorian high country.

Dangerous thunderstorms have already pummelled south-east Queensland and northern NSW on Monday and Tuesday, dropping giant baseball-sized hail in the worst-affected areas.

The ABC reports a man in his 20s suffered multiple injuries when a tree fell on his car during a “ferocious” storm that hit Orange just before midday.

Ambulance NSW said the man suffered leg, head and chest injuries. He had to be freed from his car.

Electricity was also cut to about 35,000 properties across western NSW, including Orange and Bathurst.

Ausgrid said a further 40,000 customers were without power due to the “intense storm cells” moving through Sydney and the Central Coast.

“Hardest-hit areas include Sydney’s Northern Beaches and suburbs including Erina, Gosford and Mangrove Mountain on the Central Coast,” a spokeswoman said.

“Ausgrid emergency crews are working to restore power when safe to do so, as the heavy rain and high winds continue.”

Wednesday’s wild weather comes after cyclonic winds toppled trees and brought down powerlines, shutting roads and left schools shuts as repairs continued on Wednesday.

More than 162,000 properties were left without power following the most dangerous storms on Monday.

Brisbane bore the brunt of Tuesday night’s second wave of damage from a storm system stretching as far south as NSW’s Hunter Valley, with 169 SES calls for help, followed by 148 from Moreton Bay.

Up to 110 millimetres of rain was dumped on some areas.

The Insurance Council of Australia declared the storm damage a catastrophic event, with more than 16,000 claims to date across more than 140 postcodes on Tuesday, and the damage bill yet to be tallied.

Updated claim numbers are expected to be released on Wednesday afternoon.

There is no reprieve for the east coast as dangerous storms are predicted for late on Wednesday.

“Severe storms are possible right along the coast,” Bureau of Meteorology’s Miriam Bradbury said.

“That extends from the southern parts of the Cape York Peninsula all the way through the eastern districts of Queensland and into the southeast, then pushes down across northeast and central NSW.

“For communities which have already seen a few days of very strong, severe storms, this is yet another day of very unsettled weather.”

The bureau issued a severe weather warning for the Victorian alps on Wednesday afternoon.

“A front moving through eastern parts of the state is triggering a line of showers and thunderstorms, which is moving swiftly towards the east. With strong winds aloft present across the warning area some of these storms are capable of producing damaging wind gusts,” it said.

The third day of storm warnings across eastern Australia came as authorities raised bushfire alerts to their highest levels in more than two years for some parts of NSW.

More than 20 public schools in central NSW were closed on Wednesday after the state’s Rural Fire Service issued a warning for catastrophic fire danger.

The lower central-west plains – including Dubbo, Parkes and Forbes – faced the highest level of bushfire conditions, meaning people there should consider leaving fire risk areas and stay out of paddocks and bushland.

No region of NSW has had a catastrophic fire danger forecast since September 2023.

Extreme danger warnings and total fire bans have also been declared for millions of residents, including those in metropolitan Sydney.

“‘Winds are combining with warm to hot temperatures and really dry air and that is elevating fire dangers across the region,” the BOM’s Sarah Scully said.

There are total fire bans for a further 10 regions of NSW, including greater Sydney, Illawarra and the Hunter.

Further north, large parts of Queensland continue to swelter under heatwave conditions, with temperatures six to 10 degrees above the November average.

Meanwhile, a cold front moving across southern parts of the nation is expected to trigger stormy conditions and damaging winds across parts of South Australia and Victoria.

-with AAP