Helicopter pilot John Funnell, who has made three supply drops to Mr Donaldson, said it was now looking likely he would arrive tomorrow night or Tuesday morning at the earliest.
Mr Funnell made a supply drop to Mr Donaldson today, taking him water, food, a newspaper, portable radio, and batteries for his radios and bilge pump.
"Conditions were good out there and he was about 40 [nautical] miles from New Plymouth airport," Mr Funnell said.
"He's still about 30 hours away ... we couldn't talk to him because he's lost all his battery power."
However he said Mr Donaldson appeared in good spirits.
MetService forecaster Philippa Murdoch said 25 knot south-easterly winds were expected off the Taranaki coast tonight, and the area was experiencing three-metre swells.
Winds would change to north-easterly tomorrow and strengthen to 35 knots on Tuesday, she said.
Mr Donaldson's wife Sarah, in New Plymouth, was not fazed by the latest delay and said different arrival times were "being bandied around all over the show".
"I'd obviously like him in sooner rather than later.
"She would assess how much rest and recuperation he needed after he arrived, she said.
"I mean he's not going to be able to walk properly for a while."
A batch of homemade bacon and egg pie was planned for the homecoming hero - but only if he was able to eat properly, she said.
Ms Donaldson was looking forward to the long overdue catch up, and said the couple's four-year-old son, Zac, had been missing his father.
"It's been very difficult on all levels."
Celebratory plans for his arrival are being handled by Venture Taranaki, who were waiting for the word to set up a huge marquee with entertainment and refreshments next to the New Plymouth Yacht Club at the southern end of Ngamotu Beach.
Spokesman Antony Rhodes said it would be a big celebration.
"We're trying to rally the community to get out and welcome him in."
Customs staff would be on hand to welcome Mr Donaldson and process his immigration details, and medical staff would also be present for any health concerns, he said.
- APNZ