An Australian man trapped on a New Zealand mountain by severe weather since last week has been found alive in what's been described as an extraordinary tale of survival.

There were grave fears for the 29-year-old, who failed to return on Monday from a solo climb of Mount Aspiring in the South Island.

On Thursday night, the Rescue Coordination Centre confirmed he had been found alive "with slight frostbite" by an alpine rescue team.

Coordinator Mike Roberts said it was "extraordinary" the man was standing and waving when a helicopter found him at 5pm north of Quarterdeck Pass.

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During the nearly seven days he was out alone, the man endured winds of up to 60km/h, freezing conditions and at times heavy snow.

He was described as being "in good spirits".

"He is being provided with much-needed hot food and drinks," Mr Roberts said.

The rescuers and a paramedic have come prepared to bed-in for the night and are expected to be winched out on Friday, depending on the weather.

Strong winds, sub-zero temperatures, and heavy rain for days halted helicopters trying to reach the missing man throughout the week, with search teams earlier finding his heavier equipment at a hut.

"The pilots did an amazing job to fly in and out, despite the low cloud tonight. It has just hung around the mountain for days and hampered our search efforts," Mr Roberts said.

The climber's locator beacon had been moving throughout the week.

He entered the national park on Friday and is thought to have left his heavier gear behind to make a quick ascent — not unusual practice for climbers — before being caught out by the weather.

AAP