The Australian soldier trapped on Mt Aspiring since Monday would likely not have lasted another night, say those who found him.
The 29-year-old climber was trapped in poor weather for three nights on the mountain and dug a snow cave to survive, before rescuers located him last night.
He was believed to have mild frostbite on his hands.
Southern Lakes Helicopters pilot Sean Mullally said when they flew up the mountain yesterday evening they initially could not see him.
Conditions were too poor to attempt to winch the climber off the mountain, so they dropped off four Wanaka Alpine Rescue crew members who skied across the mountain to where his beacon was last located.
They had warm clothing, tents and food to look after him for the night.
"We flew around to see if we could spot him, and on about the fourth round the paramedic saw an arm waving," Mullally said.
The climber was lucky they spotted him.
"He is very lucky to be alive. I don't think he would have lasted another night.
"It was very cold and windy. There was a lot of fresh snow.
"We were in the area for 27 minutes, and by the time we left it had clouded over and started snowing again."
The man had mild frostbite on his hands, and it was important they got him off the mountain today, Mullally said.
"Conditions are due to deteriorate further, so we are very keen to get them off the mountain.
"We will make another attempt today from the West Coast, go in via Haast Pass.
"At this stage it will be a winch job, unless we can get onto a flatter and area and snatch and grab them."
The search and rescue operation began on Tuesday, but poor weather meant rescuers could not reach the climber until last night.
Man an "experienced climber"
Rescue Coordination Centre NZ watch leader Neville Blakemore said it appeared the man was an experienced climber.
"One of the teams found his heavy equipment at one of the huts, so we assume he got there, and made a push for an assent of the mountain, but the weather caught him out.
"We believe he made a snow cave to stay warm. He's an experienced climber, an Australian army captain so has probably done a lot of survival training.
"It he hadn't had that experience, we probably wouldn't have this outcome."
It was an "extremely dangerous" rescue mission, Blakemore said.
"For the person in trouble and for the rescuers it is extremely dangerous. There is high avalanche risk at the moment, and the weather is not ideal for flying. It takes high skill from all involved."
Conditions promising for rescue today
Senior search and rescue officer Geoff Lunt said the plan today was to send in the Southern Lakes and Aspiring helicopters as soon as the weather allowed it and remove the five men from Quarterdeck pass, Mt Aspiring.
There were another two Alpine Rescue Crew to pick up from the nearby French Ridge hut.
"The climber has been sheltering for the past two nights at the pass and he has clearly made some good decisions to be able to survive the bad weather, heavy snow and high winds," Lunt said.
The weather conditions were promising for the rescue later today.
There were 10km/h south east winds which were expected to rise to 30km/h by noon. The wind chill is minus 16C with scattered rain easing this morning.
Snow was at 1200m and the party was currently about 2300m up Mt Aspiring.
Mountaineering a high risk activity
Mountain Safety Council chief executive Mike Daisley said winter mountaineering was a high risk activity and was "certainly not for the faint of heart".
"However, there's a degree of common sense that's got to come into the planning of trips like this, especially if you're solo.
"I think he's probably sat there going over where he went wrong for many hours wondering if this would be the end for him. It would have been a bloody scary situation to be in."
Daisley said a lot of people were hoping for the best but feared the worst.
"Worryingly, we knew from our insights that 25 per cent of mountaineering fatalities in New Zealand are from Australia, so we're very glad he's been found okay," he said.
"It's an amazing outcome; The rescue agencies that coordinated and responded to this tricky situation deserve a huge thanks for their skill and tenacity."
Daisley's message to those who head into the mountains above the snowline, especially those on their own, was one of prudence and caution.
"There's been a lot of snow in the last couple of days. The NZ Avalanche Advisory for the region was on high when he set out and the winds have been a factor as well."
He advised visiting climbers to pay attention to local knowledge and to do their homework on the risks involved.
"It's a good example of where the right call was probably not to go. I know he's come a long way to tick this one off, but it's just not worth the ultimate price. If the locals aren't keen on going up, you can be sure there's a good reason why."
There's an average of 37 Search and Rescue missions for mountaineering each year and around 25,500 participants per annum.