The fog is slowly starting to lift in Wellington, and tired travellers who slept rough in the terminal while "rap music" played at 3am are starting to move on.
Many passengers say communication from the airlines has been poor, with a lack of emergency accommodation in the capital leading to them sleeping on the airport floor.
A steady stream of flights is now taking off and landing at Wellington Airport, but the flow-on effects from the cancellations and delays are still being felt.
Bronwyn and Alan Don from Brisbane were part of the group who had no option but to stay the night at the airport after their flights were cancelled.
"At this stage, we're booked into flights just after 6pm tonight, so by that stage - if our flight goes - I'd say we will have been here 30 hours," said Mr Don.
"There's no options," said Mrs Don, "so there's nowhere else to go anyway."
MetService said the fog was clearing, with the base about 130m from the ground, and a much-needed northerly was developing, which was expected to blow a lot of the fog away.
It said break-outs of sunshine would be possible in the afternoon.
Morning fog across the South Island has cleared up, with no more flight cancellations or delays.
Much of the South Island was blanketed with fog this morning, causing cancellations in Christchurch, Dunedin and Invercargill.
Only some incoming flights from Wellington have been cancelled this afternoon.
Air New Zealand said earlier it would put on extra planes to get people to their destinations.
With the capital's rental car stock booked out and city hotels full, scores of passengers slept at the airport overnight.
After flights were cancelled, passengers were told to ring their airlines and re-book. Some said Air New Zealand's phone lines repeatedly crashed.
Passengers were given blankets and bottled water, but some said they could get no information. Airport staff simply handed them a piece of paper telling them to find their own accommodation.
Those who had nowhere to go slept on the airport floors, seats or leaned on walls. Some struggled to sleep because the airport left the music and lights on.
Injured and elderly caught up in drama
Traveller Vickie Davis posted on Facebook she was "appalled" and disgusted by Air New Zealand's treatment of vulnerable people.
She helped an injured man, an 84-year-old woman and a 70-year-old diabetic.
Airline staff initially offered them only a pillow and blanket, before giving them accommodation at a hotel when they complained, Ms Davis, of Ngatimoti near Nelson, said.
She said the injured man, who was flown by helicopter for an operation in Wellington and was in pain, did not get on a flight after a mistake with the seat he booked.
"These people as they are tired, upset and hungry," she posted on Facebook.
For her part, her flight from Christchurch to Nelson was cancelled, so she was flown to Wellington, where her second flight was cancelled.
They were given taxi chits, but were sent to the wrong hotel. They returned to the airport, then it was "off to another hotel only to find no meals provided".
" young couple with no money almost weren't given a room because they had no credit card for a $100 bond," she posted.
Ms Davis wrote she got a text message saying her morning flight was cancelled. When she phoned she was told to go to the airport in the morning to re-book.
'At 3am we had rap music'
Mr and Mrs Don said the night was "fractured".
The airport opened other lounges through the security area, where people could lie down on seats to sleep.
The couple got a couple of hours' sleep - before airport staff woke everyone at 4am to shift them back to the main terminal.
"In that area they couldn't turn off the lights or the music, so at 3am we had rap music, which wasn't conducive to peace and tranquility," Mrs Don said.
"At least we got a couple of hours," Mr Don said.
When they spoke to RNZ this morning, they had been at the airport for 30 hours.
Irene and Blair Irving, from Brisbane, said there were few choices for sleeping spots.
The music and lights overnight "didn't help anyone sleep", she said.
The couple were to travel home at 2.45pm yesterday after visiting family in Whanganui. They arrived at the airport late morning "and we're still waiting", Mrs Irving said.
"We hope to get out at lunchtime today... We sit and wait."
The communication was "not very good to start with" and they could not get accommodation for less than $600 a night.
"That's why we decided to stay here."
"Hopefully we won't be here another night."
'It's every man for himself'
A quadriplegic Australian, Paul Mckenzie, who flew into Wellington with his partner, Jess, and three-month-old baby, said he would never do the trip again.
He did not want to spend the night sitting uncomfortably in his wheelchair, but struggled for hours to find somewhere to stay.
It was a "long day". They found accommodation 45 minutes from the airport, which they were likely to take. It was tough to find something suitable for his wheelchair.
"There's no back-up plan, it's every man for himself."
The family arrived early for a Qantas flight yesterday morning and were still there at 7pm.
"I've been going since 5am. My body's sore, my baby is cranky... we've had enough."
Mr McKenzie hoped he could get on a flight home today.
Passengers expected more from national airline
English lawyer Peter Wallington QC was travelling with his wife. He was "unimpressed" with Air New Zealand's customer service.
They arrived about 2pm yesterday for a 4.15pm domestic flight.
Last night he told RNZ the airline offered no help to find hotel rooms. It could have arranged buses to take passengers to Palmerston North's airport, but was told it was "too complicated".
"In almost any other country, we would expect the national airline to be able to manage that."
Mr Wallington said if the response was typical for Air New Zealand, the airline had a serious problem.
Leslie Bergsma hoped to fly to Johannesburg via Sydney with Qantas.
"Nobody's around. Every now and then they'll come past and give you a bottle of water if you're lucky. When the time comes to actually tell us what's happening, nobody wants to talk to you.
"All they want to do is hand a piece of paper to you and say to go and try and find accommodation because the whole of Wellington is full. Neat, Qantas."
Wellingtonians offer beds to stranded
One Wellington man invited stranded passengers to stay the night at his house.
Two passengers took up Jeff Weir's offer when he went to the airport last night from his Strathmore home.
He told Morning Report one was in transit from Taranaki to Fiordland on a hunting trip and another was an Australian woman bound for Canberra.
He said others heard what he was doing and followed suit.