The South Island's biggest city has issued a state of emergency due to flooding, which has impacted the CBD and outlying towns including Doyleston.
Christchurch has been lashed with 100mm of rain in the 36 hours to 4pm on Thursday, prompting the declarations and a small number of evacuations.
The mighty soaking is almost double what the city usually receives in the month of May.
"We expected the weather would ease, which hasn't happened," Christchurch Mayor Phil Maugher said.
"We need to make sure we're able to keep people safe by putting all of our resources into responding to any problems that arise and one of the best ways we can do this is by declaring a Local State of Emergency."
Further north in the capital, forecasters MetService have warned of a "threat to life", urging people in exposed areas and on the south coast to stay home
"Threat to life from flying items and falling trees. Destructive winds will cause widespread damage including powerlines and roofs, with dangerous driving conditions and significant disruption to transport and power supply," their warning states.
Social media is packed with pictures of broken windows, displaced trampolines and damage to fences and roofs.
The red weather warning is the first issued anywhere in New Zealand this year and Wellington's first since the system's introduction in 2019.
"Wellington is no stranger to high winds but even by our standards this is an extraordinary day in the capital," MetService meterologist John Law told AAP.
Mr Law said the "combination of wind direction, a strong southerly, and rainfall and higher tides" has prompted the warning escalation.
The highest gust was recorded at Mount Kaukau, an exposed point in the city's north, at 150km/h, with the airport on the south coast registering 115km/h.
All flights have been cancelled for the day, with Radio NZ reporting just one exception: a Qantas flight from Sydney due to land at 11.55pm which may go ahead.
The vicious southerlies are predicted to subside late on Thursday - though swells are expected to stay large, with an elevated coastal risk around 8pm at high tide.
Cook Strait ferry operators have also cancelled sailings through to Friday at the earliest.
The huge storm has also brought the first major snowfall for the season further south, with news outlet Stuff publishing pictures of a thick snow blanketing the inland town of Tekapo.
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