The Bureau of Meteorology has issued a severe weather warning over a cold front set to hit the south-east of New South Wales this evening, bringing dangerous conditions.

The front is generating strong north-west to south-westerly winds, with the wind chill factor worsening the cold temperatures of about 11-15 degrees Celsius forecast for Sydney on Saturday.

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Winds of up to 90 kilometres per hour are expected to lash the Sydney metropolitan area, the Illawarra, the northern South Coast, the Central Tablelands, the Blue Mountains and the Southern Ranges on Saturday.

In alpine areas above 1,900 metres, winds could hit 120kph, the bureau said.

The cold front is also bringing blizzard conditions at areas above 1,600 metres, with the NSW National Parks and Wildlife Services advising against back-country travel until conditions improve.

Areas affected include Wollongong, Nowra, Bowral, Batemans Bay, Moruya Heads, Katoomba, Goulburn, Cooma, Bombala, Thredbo and Perisher.

Perisher Ski Resort said it had experienced snowfall of 25 centimetres overnight, bringing its total to 54cm since Wednesday.

Thredbo said it had been hit with 15cm overnight.

The NSW State Emergency Service has advised people to prepare for the adverse conditions.

"Please ensure you secure loose items and move vehicles undercover or away from trees," the SES said on Facebook.

BOM said conditions were expected to ease later on Saturday.