A woman caught in a blizzard while tramping in Nelson Lakes National Park died from severe hypothermia after battling the extreme conditions on Saturday night.

The family member she was tramping with made it to Angelus Hut during the night to raise the alarm after they were unable to get cellphone reception.

But the 55-year-old woman spent the night exposed to the elements, battling a -16C chill and blustery 80km/h winds.

The woman was already dead when the Nelson Marlborough Rescue Helicopter reached her at 9am today. She was found in a gully on Mount Robert Ridge.

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Police Search and Rescue co-ordinator Sergeant Malcolm York said police extended their sympathies to her family and friends.

"One of the party members made it through, while the deceased wasn't able to."

Victim Support is assisting the family.

"This is a truly tragic incident that followed what could have been another unfortunate event the evening before," York said.

At around the same time the two family members got caught out by the wind and snow, another couple in their 40s were also heading to Angelus Hut when they got stuck in the blizzard.

Unsure whether to keep heading up Mount Robert Ridge, they managed to get mobile phone reception from the ridge they were on and called Police for advice about 4.30pm.

York said while the two parties' locations were not far apart, one group had mobile phone reception and the other didn't.

York called the couple back moments later and using their GPS position advised them to start heading down towards the car park.

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The couple kept walking until it got dark and found shelter beside some rock where they used their gas cooker to make hot drinks to warm them up while they waited for the search and rescue helicopter.

They were located about 1800 metres above sea level and about 4km from their intended hut.

Nelson Marlborough Search and Rescue Helicopter pilot Duncan Gourley said there was a lot of snow blowing around and visibility was poor.

"It was alpine country - rocks and snow."

About 7pm the helicopter spotted their torches and hovered overhead while the couple were pulled onboard.

Within 10 minutes the couple were dropped to St Arnaud where police took them to a nearby residence to warm up.

If the weather had been any worse the rescue chopper would not have been able to pick them up, Gourley said.

"It was probably on the limit. With the wind and it was dark and there was a bit of blowing snow. It wouldn't have wanted to be any worse - we were at the maximum of our capabilities doing that I would say."

York said the strong winds and snow did not make it appropriate tramping conditions and urged people to make good decisions based on the weather.

"It is important to monitor proposed weather conditions and make good decisions around them, and the risk that inclement weather poses to your intended trip. Consider the time of day you are setting out, know your limitations and make sure you have appropriate clothing and equipment with you.

"Thankfully yesterday the trampers were located in time, but it could easily have been a different story."

ADVICE FOR TRAMPERS

• Plan your trip
• Tell someone reliable your plans
• Be aware of the weather and make good decisions around it
• Know your limits
• Make sure you are adequately equipped for your intended trip
• Take sufficient supplies