Southern NSW is set for an "excellent" early opener to the ski season, with clear skies and light winds to greet skiiers at Perisher this weekend.

The resort will open this Saturday, a week ahead of schedule, after 20 centimetres of snow was dumped on the Snowy Mountains four days ago.

Other resorts including nearby Thredbo will open next weekend.

Gentle winds and icy conditions have made "ideal" weather for snowmaking machines, which are expected to run until the weekend when some of the snow will begin to melt.