Temperatures across NSW and the ACT are expected to plunge by up to 10 degrees Celsius, as a cold front brings gusty winds a snow falls to some parts of the state on Friday.

Key points: Temperatures could drop by up to 10C in Sydney between Thursday and Friday

Temperatures could drop by up to 10C in Sydney between Thursday and Friday Snow falls are expected in the Southern Tablelands and alpine regions down to 1100 metres

Snow falls are expected in the Southern Tablelands and alpine regions down to 1100 metres It's the first significant cold front of the season, after an unusually warm autumn

The Bureau of Meteorology (BOM) said the cold front moving north from the southern ocean would bring a very cool and gusty change.

"The wind that we're seeing with this system coming through tomorrow will provide a lot of wind chill so the temperatures that you'll see on the forecast might not tell the whole story," senior forecaster Jake Phillips said.

He said the wind-chill could bring the apparent temperature down by 5-10C.

"For Sydney … we're forecasting around about 20 degrees but at times it could feel more like 12 or 13 degrees — and that's during the daytime," he said.

Temperatures in the west of the state will be well below average for this time of year — in some by as much as six or seven degrees during the day.

"It could be a bit of a shock to the system," he said.

"It is a very significant change.

"We've seen an unusually warm autumn but this is actually the type of system we do expect to see this time of year, so it's actually a return to some normality."

Snow showers are forecast to hit the Southern Tablelands and alpine areas in the morning, as low as 1100 metres, while some elevated parts in the western Central Tablelands can expect light snow by afternoon and evening.

The white stuff will be welcome for the state's ski resorts, with snow cams revealing a light dusting of powder on some runs and nothing but grass on others.

Temperatures at the top of Thredbo hit -2 degrees on Thursday, but it was -10 degrees with the wind chill.

The state's ski resorts will welcome any snow they can get. ( Supplied: Thredbo )

Perisher's website said the resort woke on Thursday morning to a dusting of snow, with more set to roll in on Friday and into the weekend.

"The snowguns have started to blast for the 2019 season and the snowmaking team will begin firing up the guns at every opportunity," it said.

Mr Phillips said the "rapidly moving" system should clear the state and move over the Tasman Sea by Saturday prompting warnings of possible hazardous surf conditions.

"We'll actually be left with a fairly pleasant weekend, a little bit gusty still on Saturday but some beautiful days, however the mornings will be rather cold," he said.