A gale force southerly has slammed Wellington- grounding flights, flooding streets, and even ripping part of a wing mirror off a car.
Evening commuters are facing long queues at the city's central train station, with many services being replaced by buses due to "adverse weather conditions".
Melling services are running as shuttle buses between Petone and Melling. Services between Wellington and Upper Hutt, and Wellington to Masterton, are being replaced by buses.
Metlink said limited capacity was available and urged people to arrange alternative transport where possible.
"We know this is frustrating for passengers wanting to get home and we'd like to thank commuters for their patience and understanding.
"With unpredictable weather, however, avoiding cancellations isn't always possible and we encourage passengers to ensure they have alternative travel options in place."
Gain said there were also detours in place for several bus routes due to slips or debris on the roads.
"In such inclement weather, people are more reliant on our services, and we will endeavour to avoid bus cancellations by introducing detours around affected areas."
There are numerous weather watches and warnings across the region, including heavy swells, severe rain, strong wind, and snowfall.
Metservice reported today's "troublemaker" was a deepening low pressure that could be clearly seen swirling to the east of the lower North Island.
High winds tore the roof from Normablue Cafe in Lower Hutt shortly after midday with a "bang". Some of the customers were shaken up, but nobody was hurt.
Most flights to and from Wellington Airport are suspended or delayed until further notice.
The airport advised on Twitter that some jet flights may be able to land and take off today, but this is weather dependent.
Passengers have been told to check directly with their airlines.
A Bluebridge ferry attempted to leave Wellington this morning before the weather hit and was forced to return back to shore with the help of a tugboat.
Monster waves could be seen hitting the city's south coast where one gust of wind was so strong it twisted off a section of a car's wing mirror.
The vehicle was parked at Waitaha Cove when it happened.
MetService meteorologist Luis Fernandes said a 10m wave was recorded south of the harbour at about 11am, and there were regular waves reaching 6m.
In the Hutt Valley, the river has reached 2.5 metres higher than usual and is threatening the Riverbank carpark.
A stretch of road in Eastbourne has also been closed because of waves breaking over it.
Today's trouble maker - a deepening low pressure - can clearly be seen swirling off the east on the satellite loop. A gradual improvement will take place overnight but for now several watches and warnings remain in effect. More at https://t.co/qHyE5zzql5pic.twitter.com/8NqKjhJkrt