Two people are reportedly dead and the wife of Gareth Morgan has miraculously survived after a major avalanche in the South Island this morning.

Jo Morgan reportedly survived the major avalanche on Mt Hicks by digging herself out of snow - and set off a locator beacon.

The daughter of Jo Morgan, Jessi, wrote on Facebook: "Just an update that Jo is safe and back at Mt Cook village. Thanks for all your support and messages."

A major search operation was launched after the avalanche on Mt Hicks, near Mt Cook, this morning.

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Rescue Coordination Centre NZ mission coordinator Nev Blakemore told 1 News a woman had dug herself out, but two men remained buried.

1 News is reporting the two climbers have died.

Rescue Coordination Centre spokesperson, Grace Loftus says the alarm was raised early this morning by an experienced woman climber who was with the two guides.

That climber is thought to be philanthropist Jo Morgan - wife of Gareth Morgan.

Morgan posted on Facebook yesterday conditions has been bleak at Empress Hut the last couple of days but said a 20-hour weather window meant they would plan to leave for Mt Hicks at 2am on Wednesday.

Rescue teams and rescue helicopters raced to Mt Hicks after receiving the locator beacon signal, a Rescue Coordination Centre New Zealand spokesman said.

Two helicopters, eight alpine cliff rescue people and an avalanche dog are out searching.

A helicopter with medical supplies is also on its way from Christchurch.

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Rescue coordination centre media spokeswman Grace Loftus doesn't know what time the emergency was first raised, but she was notified at 6.45 am.

Mt Hicks, 3198m, is a mountain in the Southern Alps within the Mount Cook National Park.

Gary Dickson, who has more than 30 years of climbing experience, said if the rescue was on Mt Hicks it was a mountain that was tricky and one of the more difficult mountain climbs in New Zealand.

The Alpinism and Ski owner operator said the climbing difficulty in Mt Cook Regional Park was scaled from one to six. The easiest route on Hicks was a 4, while there was some that were a 5.

There were several routes up the mountain, the most popular was the south face which was a series of steep climbs.

"It's steep ice climbing for New Zealand," he said. "There is an awful lot of difficult climbs there."

Avalanche Advisory New Zealand (AANZ) has warned of rapidly changing volatile spring conditions in the Aoraki/Mount Cook National Park area.

A spokesman said a high degree of caution was advised until 10am tomorrow.

Dangerous avalanche conditions, careful snowpack evaluation, cautious route-finding and conservative decision-making was essential from above 1400m, he said.

The latest advisory at www.avalanche.net.nz says there is a considerable risk of avalanches in Arthur's Pass, Craigieburn Range, Mt Hutt and Aoraki/Mt Cook.

Avalanches can happen at this time of year as the warmer temperatures, combined with rain, increased risk.

A week ago three hunters had a lucky escape after an avalanche brought snow crashing onto their tents in Fiordland, at the head of Lake Te Anau.

The incident also follows the death of Caleb Jennings earlier this month.

The 31-year-old was seriously injured while climbing near Mt Harper, in Mid Canterbury, on October 22. He died in Christchurch Hospital three days later.

Jennings had been a member of the New Zealand Alpine Team.

More than 140 people have died in avalanches in New Zealand, according to records that began to be kept in 1860.

One of the worst incidents happened in August 1863 when a massive avalanche buried a camp of goldminers in Otago, killing 41. In modern times avalanches most often claim the lives of climbers.

Another tragedy occurred on June 23, 1966, when a rescuer was killed in an avalanche during an unsuccessful attempt to rescue four climbers trapped on Mt Rolleston.

In 2015, Sydney skier Roger Greville died after being pulled from avalanche debris near the Devil's Staircase, near Queenstown.

More to come