A seriously injured German tourist who fell more than 10 metres into a crevasse at Fox Glacier today (Thur) will have to spend the night there with her rescuers.
The woman fell near Pioneer Hut about 3pm, and her boyfriend raised the alarm at a nearby hut.
A search began about 3.30pm and rescuers reached her at 6pm.
A rescue helicopter was unable to reach the scene tonight because of low cloud.
MetService forecaster Liz Walsh said the very low cloud in the area would increase.
The temperature at the glacier could get as low as 5C overnight, she said.
Rain was also forecast. "It's due to get cloudy again in the morning, which could hamper rescue efforts,'' Ms Walsh said.
The rescue crews were trying to keep the woman warm and stabilise her condition, West Coast Search and Rescue coordinator Sean Judd told Radio New Zealand.
The three rescuers are well equipped.
"Having said that, it will be a fairly uncomfortable and cold night on the hill, but they are certainly equipped to handle a night out,'' Sergeant Judd told Newstalk ZB.
He hoped the helicopter would soon be able to winch the woman and her rescuers out of the crevasse.
The rescue effort will resume at first light.