A severe weather warning was issued for the ACT, Snowy Mountains and Southern Tablelands in the early hours of Wednesday morning, with parts of the Illawarra, South Coast, Central Tablelands and South West slopes also likely to be affected.

The Bureau of Meteorology said winds averaging 55 to 65 km/h were possible in Queanbeyan and the ACT and could reach more than 90 km/h in areas above 1900 metres.

"Blizzards are also possible," the bureau said.

While Queanbeyan enjoys a relatively balmy 20 degree day, the strong northwesterly winds will move into the area ahead of an approaching cold front. 

And pack the brolly - there's likely some rain on the way as well.

The State Emergency Service advised people to move cars under cover and away from trees, keep clear of fallen power lines and secure loose items around their homes

The National Parks Service of NSW recommended people consider postponing back country travel until conditions improve.

Locations which may be affected include Queanbeyan, Canberra, Bowral, Braidwood, Orange, Bathurst, Katoomba, Goulburn, Cooma, Yass, Bombala, Nimmitabel and Khancoban.