Snow could cut power to 2500 NSW homes

Up to 2500 homes in Blue Mountains have been warned that they could lose power overnight, after spring snow hit the region west of Sydney.

Power supply was interrupted in Blackheath, Mount Victoria, Medlow Bath, the Megalong Valley and Leura today due to strong winds and snowfall.

"Snow on road access has hampered our ability to patrol the network and make repairs to safely restore power supply," Drew Ferguson from Endeavour Energy said in a statement.

"We are hoping an expected break in the weather later this evening will allow us to use a helicopter to survey the damage from the air."

More than 300 motorists were rescued and taken to emergency refuges as spring snow brought traffic to a standstill - and sparked snowball fights and other fun.

Snow was reported at Bungendore, Moss Vale and Goulburn on the southern tablelands, Orange and Blackheath on the central tablelands, and Guyra on the northern tablelands.

Drivers were stranded as the Great Western Highway in the Blue Mountains became impassable, with slicks of potentially deadly black ice developing as temperatures plunged.

The road was shut between Bullaburra and Mount Victoria, forcing motorists to shelter in refuges set up at Medlow Bath, Katoomba and Blackheath.

Emily Lambert, team leader at the RSPCA Blue Mountains Animal Shelter, arrived to work in Katoomba and found several centimetres of snow.

"The animals found it quite funny. One border collie didn't know what to make of it and ran around, trying to chase the snow flakes," she told AAP.

Blue Mountains City Councillor Don McGregor said the snow was "beautiful".

"It's the thickest fall we've had for at least 10 years," he said. "I'm no skier, but I'm confident I could ski on it."

The SES received 360 calls as fierce winds brought trees down and damaged roofs in the Illawarra, southern highlands, Sydney and NSW south coast.

A fresh severe weather warning was issued by the Bureau of Meteorology at 5pm (AEDT), forecasting wind gusts of up to 100kmh in the coastal parts of the Illawarra, Sydney and the Hunter, with large seas for the southern and central coast.

People in Sydney, the Illawarra, the Hunter and south coast were told to steer clear from the surf, as an "intense" low pressure system moves slowly northeast.

"Gale-force winds, localised heavy rain and large swells are being generated near and to the south of this system, although conditions are expected to ease through the night," the BoM said.

Since the wild weather started 24 hours ago, more than 230mm of rain has fallen in Ulladulla on the south coast.

Sheep graziers across much of the state are being warned of more cold temperatures and southwesterly winds during Friday night and into Saturday with a high risk of losses of lambs and sheep exposed to these conditions, the BoM said.

Forecasters say temperatures will rise over the weekend and winds will ease, as the low-pressure system moves offshore.