Wellington's weather was so wild yesterday that a wave-height monitor was washed away across the harbour.
The Lower Hutt suburb of Eastbourne was completely cut off by large swells and debris. Roads on Wellington City's south coast were also closed after rocks from the seawall ended in the path of motorists.
Flights were disrupted and ferries across the Cook Strait cancelled.
By pure coincidence, regional and city councillors were visiting what is the maritime equivalent of an air traffic control centre on Beacon Hill at the time of the storm.
The signal station is staffed 24 hours a day and is the first point of contact for ships arriving to and departing from Wellington Harbour.
Greater Wellington Regional Council chairman Daran Ponter was among those elected members visiting the site when reports came in the wave height recorder had gone awry.
"The state of the sea was so bad, that the wave height recorder had come loose and washed across to the lighthouse on the other side of the strait," Ponter said.
"You could see a big set of waves coming through the channel into the harbour. It was quite impressive and at that time they were an average of about 5.5m."
Harbourmaster Grant Nalder confirmed Niwa had gone to retrieve the monitor, which has GPS tracking, from Fitzroy Bay this morning.
He said the monitor was about 1m in diameter and looked like a big yellow ball with a clear dome at the top to accommodate its solar panels.
"It sits there and goes up and down with the waves and the sensors inside measure how far it moves and how often and you get a whole heap of data about the sea conditions and the swell in the waves."
Yesterday's wild weather comes just three months after a weekend storm caused significant damage across the city.
Wellington was drenched with one-in-10-year rainfall resulting in flooding, slips, fallen trees, wastewater overflows, evacuations, and damage to private property.
The suburb of Khandallah experienced one-in-30-year rainfall, meanwhile Miramar was saturated with one-in-60-year rainfall.
A review of the storm event was tabled at a council Infrastructure Committee meeting today, warning that more slips and floods will be a part of Wellington's future.
"We will need to adapt our infrastructure and our expectations as this occurs with increasing frequency in the coming decades," the review said.
It reported the council's contact centre was "overwhelmed" over the course of the weekend answering 680 calls, which is four times the usual amount.
Almost 70 homes were "compromised" from stormwater flooding, or wastewater, or both.
The review said in some areas, investing more in infrastructure would not be able to solve the problem.
"Development in the lowest-lying areas, adjacent to streams or in former lakes will increasingly be at risk.
"Wellingtonians are going to have to learn to live with more water, and to plan our city accordingly."