Cold swells of up to two metres and winds of more than 100km/h have been hampering efforts to save stranded pilot whales in the Far North.
The whales came ashore on Wednesday and are stretched over 5km of beach at Spirits Bay.
Twenty-four were still alive on Thursday night, while up to 50 are believed to have died.
A spokesperson for the Department of Conservation says rescuers have been trying to shift the surviving mammals to a nearby stream.
Sioux Campbell says the surf is too rough at Spirits Bay to refloat the whales and they will be hoisted onto trucks and transported 50km to Rarawa Beach where they will hopefully be released on Friday.
In August, about 60 pilot whales were stranded on the Karikari peninsula in the Far North. Fewer than a quarter survived.