Sydney has been warned to rug up for a “blast of winter”, as snow was dumped on the New South Wales ski resorts ahead of possible blizzard conditions.

The maximum temperature in Sydney is expected to reach just 17 degrees on Friday, with a minimum of 9 degrees overnight.

It follows a warmer than average start to autumn, with the monthly average 5.5 degrees above the May long-term average so far.

“Dig out your winter coats,” the Bureau of Meteorology warned.

“An early blast of winter later this week. Cold, blustery winds with possible snow along parts of the southern/central ranges on Friday.”

The weather bureau said the maximum temperature in Perisher would be just 1 on Friday, and 6 in Orange.

Sydney is expected to be a mild 20 degrees on Saturday and Sunday, with showers over the weekend.

A severe weather warning is in place for damaging winds expected to develop on the ranges on Friday.

“A complex low pressure system near Tasmania is deepening in response to a cold front crossing the region,” BoM said.

“This low is expected to slowly move east resulting in vigorous winds across south-eastern and elevated parts of the state on Friday.”

Wind gusts in excess of 90km/h are expected to batter the ranges and Illawarra district from late Friday morning.

A southerly change is then expected later on Friday.

Blizzard conditions are possible in alpine areas above 1700 metres, with peak gusts in excess of 120km/h following the southerly change.

National Parks Service of NSW recommended postponing rural activities until conditions improve.

Vigorous southerly winds could also hit Nowra, Armidale, Orange, Canberra, Goulburn, Thredbo and Yass.

A gale warning is in place for the Hunter Coast, Illawarra Coast, Batemans Coast and Eden Coast. The Byron, Coffs, Macquarie and Sydney coasts have a strong wind warning for Friday.

Sheep graziers were warned the weather could pose a risk to lambs and sheep on Thursday and Friday.

“There is a risk of losses of lambs and sheep exposed to these conditions,” BoM said.

Areas covered by the warning included the Illawarra, South Coast, Southern Tablelands, South West Slopes, Riverina, Snowy Mountains and the ACT, as well as Central Tablelands, Central West Slopes and Plans and Lower Western forecast districts.