All flights in and out of the capital have been grounded until further notice as gale-force winds and torrential rain lashes the region.
There's chaos across the region, with several roads closed and power outages affecting hundreds of homes.
High winds have ripped the roof of a cafe in Lower Hutt.
Normablue Cafe manager Gillian Giles said the incident happened shortly after midday.
"We just heard this sort of, I don't know, kind of a bang, and next thing you know bits of the roof are flying everywhere and there's a great big overhang of roof over the shop."
Fire and Emergency was on hand at the Waterloo business to help, and a group of builders working on a job down the street would assist with repairs, she said.
"It's just a bit crazy, really."
Some of the customers were "a little shaken up" but nobody was hurt.
Giles urged other Wellingtonians to stay safe in the wild weather.
There are numerous weather watches and warnings across the region, with MetService urging people to keep up to date with the latest.
Meteorologist Luis Fernandes said a 10m wave was recorded south of the harbour about 11am, and there were regular waves reaching 6m.
The wind gusts at the airport were also consistently reaching speeds higher than 100km/h, with one recorded at 113km/h.
A weather warning remains in place until late tonight, but Fernandes said it should start to ease as the afternoon went on.
Pattrick Smellie was at Wellington Airport after his flight was cancelled, and said the scenes were "relatively chaotic".
📣 ALL FLIGHTS in and out of Wellington Airport have been cancelled until further notice due to adverse weather conditions. High winds are making it unsafe for baggage handlers to operate. Passengers are advised to check directly with their airlines for further information.
— Wellington Airport (@WLGAirport) July 20, 2022
There were "vast queues" of people at the airport trying to figure out what to do next, exacerbated by the fact Air New Zealand had only limited seats available for the next two or three days.
He said the weather outside was "extremely wild" and he had one colleague whose car boot came down on their head today due to the force of the wind.
A Bluebridge ferry which attempted to leave Wellington this morning before the weather hit is being assisted back to shore by a tugboat, with harbourmaster Grant Nalder telling the Herald it had been in the harbour since 9.30am.
In the Hutt Valley, the river has reached 2.5m higher than usual and people are being urged to move their cars from Riverbank carpark, which will soon flood.
RIVERBANK CARPARK: The Hutt River is currently at 2.5m. Due to unpredictable weather it is advised that you move your vehicle as soon as possible if you are using this carpark. Alternate parking is available in HC2, HC3 & HC4 zones. For more info please call 04 570 6666
— Hutt City Council (@HuttCityCouncil) July 21, 2022
The wild weather also closed roads - including a stretch of busy Willis St.
The road was closed between Mercer and Boulcott St because of concern over the stability of a window in a building.
Wellington City Council spokesman Richard MacLean said Willis St reopened just before midday.
A stretch of State Highway 58 has been closed to westbound traffic due to a slip.
Waka Kotahi New Zealand Transport Agency says the road is closed between the intersections with Postgate Drive and Spinnaker Drive but eastbound remains open.
People should expect delays.
A stretch of road in Eastbourne has also been closed because waves are breaking over it.
A yacht has also been smashed against a seawall in Lowry Bay, and Nalder told the Herald people are working to remove its mast, as it's blocking the road.
"The first objective is getting the road clear, and then working with the owner of the yacht as it's sustained quite a bit of damage."
Nalder says the conditions are nasty and it's "not a day to be out on the water".
"It's supposed to carry on all day and then start dying off tomorrow ... but it is going to be windy all day today."
People are advised to avoid Marine Drive in Eastbourne because of the chaotic weather.
⚠️Update from @HuttCityCouncil: Marine Drive & Seaview Drive are closed at the Gracefield intersection due to impacts from severe weather. Port Road is closed. There's surface flooding along Randwick Drive, & Waiwhetu is facing surface flooding. Take extra care & avoid travel.
— Wellington Region Emergency Management Office (@WREMOinfo) July 20, 2022
Petone foreshore is also being battered by waves, with National MP Chris Bishop posting video showing the chaotic conditions.
Stay safe folks. pic.twitter.com/CCpP3fSXjk
— Christopher Bishop (@cjsbishop) July 21, 2022
Almost 900 people are without power in Eastbourne and Wainuiomata, with it unlikey to be restored for more than an hour.
Wellington Electricity says 890 homes are without power, and it will be another 112 minutes untl it's expected to come back on.
Wellington City Council reported flooding wasn't a major problem at the moment, but there were some issues in Makara and Aro Valley.
Contractors have been dispatched to several incidents across the city, including a dangerous tree and "dancing" manhole cover.
There is a large slip on Severn St in Island Bay, as well as slips on Houghton Bay Rd, Old Porirua Rd, Shelley Bay Rd, and Hutchison Rd.
Almost all ferry sailings have been cancelled because of high swells with forecasts of up to 7m, and the Wellington City Council is warning people to be aware of the flood risk as the day goes on.
There are also snowfall warnings on the Desert Rd and the Remutaka Hill Range, with the Desert Rd getting 2-3cm of snow near the summit.
Sleet is expected on the Remutaka Range and there's a chance it could turn to snow, MetService warns.
Wellington and Wairarapa will also be blasted by gale-force winds and torrential rain with gusts up to 130km/h in exposed places.
In Wellington, there have been 16 slips in the past 24 hours, from Maupuia to Houghton Bay to Te Aro and Kaiwharawhara.
Motorists are advised to avoid Lennel Rd in Wadestown following a significant slip. It's not yet know when it will be cleared.
Some trains in the Hutt Valley are also cancelled and have been replaced by buses due to the poor weather.
"While flooding isn't a major issue at the moment, large waves are forecast for this afternoon and, given all the adverse conditions, we recommend everyone travel safe, stay dry, and report any major weather incidents to our contact centre on 499 4444," a council spokesman said.
🟧 Severe Weather Update 🟨
— MetService (@MetService) July 20, 2022
Snow, rain, wind and swell warnings/watches are on the cards around central parts of the country today.
Get all the details here: https://t.co/qHyE5zhh6X
Make the most of the weekend as more wind and rain approaches from the north early next week. pic.twitter.com/S0bvvp3JnW
A heavy swell warning is in place for Wellington from Cape Terawhiti to Turakirae Head. Swells are expected to peak at 7m early this evening, and will be between 5m and 7m through tomorrow afternoon.
Wellington Regional Emergency Management is warning people to stay off the beaches and avoid driving on coastal roads during peak swells.
"Swells can cause surface flooding and debris wash up including driftwood, seaweed, sand and gravel."
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