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.
