Thousands of travellers have had their Christmas plans thrown into turmoil after fog at Wellington airport today forced the cancellation of more than 100 flights.
A thick, low fog rolled in during the afternoon, forcing both Jetstar and Air New Zealand to cancel all flights into and out of the capital for the rest of the day.
An Air New Zealand spokeswoman said about 100 flights had been cancelled, causing disruptions to "several thousand passengers".
Services were not due to resume until 9am tomorrow.
"Air New Zealand apologises for the inconvenience to passengers at this busy time of year; however, the fog conditions are such that it is impossible to continue normal operations."
The airline was looking at putting on extra flights into Wellington tomorrow to accommodate disrupted passengers.
A Jetstar spokesman said eight flights between Auckland and Wellington and four flights between Wellington and Christchurch had been cancelled.
Six more flights had been added to the schedule tomorrow to accommodate travellers whose flights were disrupted.
"It's unfortunate timing before Christmas Eve, but I guess the weather is the weather," the spokesman said.
"We've got plenty of seats and we've put extra services on to get, I imagine, everyone into Wellington for Christmas."
Former TVNZ news boss Bill Ralston had been due to fly to Nelson via Wellington but was among the hundreds of passengers stuck in Auckland.
"I'm at the airport. It's madness," he said.
"They cancelled three flights in a row, at once, so there was a mad rush for the baggage hall, and then everybody was wandering around in circles wondering what to do next."
He said people seemed to be in remarkably good spirits despite the cancellations.
Ralston said he had "retreated to a nearby airport hotel" and had booked a direct flight to Nelson for tomorrow.
Wellington Airport spokesman Greg Thomas said today's thick fog was unusual.
"It doesn't usually last this long, and it's quite set in at the moment. There's a southerly breeze blowing but the fog just doesn't seem to be letting up at the moment."
Mr Thomas said passengers should check their flight's status on the airport's website or with their airline, and in some cases they may need to re-book their flights.
MetService duty forecaster Philippa Murdoch said the fog could stick around until at least tomorrow morning.
Before the cancellations, flights out of the capital had been delayed by at least three hours, while others had been diverted to Palmerston North or Nelson.
Fog also brought Wellington Airport to a halt on Tuesday, with about 40 flights in and out of the city cancelled.
Meanwhile, MetService this morning issued a severe weather warning for the upper North Island, as the remnants of Cyclone Evan pushed over the country just in time for Christmas.
A deep low - which was formerly the cyclone - would lie north of Northland tonight, then just west of Cape Reinga by the end of tomorrow, before drifting to the west of the North Island on Christmas Day, MetService advised.
Rain was expected to become heavy this afternoon, and continue through Monday and into Christmas Day.
The heaviest rain would hit Northland, Auckland north of Whangaparoa, and the Coromandel Peninsula north of Tairua.
MetService warned holidaymakers and trampers that rivers and streams could rise rapidly and that slips and surface flooding was possible.
Ms Murdoch said the rain in Northland would become heavy this evening, and then ease in the morning.
There could then be another burst of heavy rain on Christmas Day in the upper North Island.
WeatherWatch analyst Aaron Wilkinson said by Boxing Day the low would weaken and move east, bringing a period of rain to most of the country.
The lower South Island could remain fairly dry, he said.