Part of Tamaki Drive on Auckland's waterfront is closed due to flooding as a king tide hits.
Auckland Transport said the road, a main route to the city for commuters, was closed between Ngapipi Road and Hobson Bay area.
All Gulf Harbour ferry services had also been replaced by buses due to bad weather.
UPDATE 7:30AM - Tamaki Drive is NOW CLOSED between Ngapipi Rd the CBD (Hobson Bay area). Diversions are being set. Please use an alternative route. ^TP— Auckland Transport (@AklTransport) January 31, 2018
A severe weather warning is in place for most of the country as former Tropical Cyclone Fehi arrived overnight.
An RNZ staff member said the Tamaki Drive closure had backed up the eastern suburbs with Remuera Drive and access onto the southern motorway at Greenlane and nearby streets jammed.
He said it had taken half an hour to drive a couple of kilometres along Remuera Drive this morning.
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MetService duty forecaster Raveen Das told Morning Report that the cyclone had turned into a deep low over the Tasman Sea.
The low was forecast to move south east across the country today bringing heavy rain and severe gales to most places, he said.
The West Coast of the South Island was expected to bear the brunt of the weather, with significant rain forecast.
Widespread rain with heavy falls continues over much of the South Island. Rain also moving into Northland and Taranaki ^AD pic.twitter.com/l92jrj0jxg— MetService (@MetService) January 31, 2018
Lower Westland and Fiordland were reporting rainfall rates of about 15 - 20 millimetres per hour and that was expected to go up to about 40mm per hour.
Heavy rain was also expected for Mt Taranaki and Tararua Range.
The strongest winds were likely to be in Westland, Buller, Canterbury High Country, Nelson, Marlborough , Wellington and southern Taranaki, and a Strong Wind Warning is in force for these areas, MetService said.
RNZ Reporter Tracy Neal, who is in the small coastal town of Glenduan just outside of Nelson, said the wind was starting to pick up and a large swell was starting to roll in.
She said a high tide was expected to hit about midday and there would be swells of up to five metres.
And residents in the low-lying coastal suburb of Monaco in Nelson have put up storm gates on properties that front the sea.
The swell is already washing over parts of State Highway 6 along the Nelson waterfront, and is threatening properties at Ruby Bay in the Tasman District.
Civil Defence controller Roger Ball said campers in low-lying coastal areas had been advised to leave.
Southland has activated its emergency co-ordination centre as the dry spell finally broke.
Farmers were moving their stock to higher ground ahead of the storm.
West Coast Federated Farmers president Katie Milne said all rivers in the area were prone to flooding and farmers needed to be vigilant with their stock.
Today's weather forecast
Showers, then rain from late morning, downpours and possible afternoon thunder. Strong, gusty northeast, changing southwest overnight. High 25°C; Low 19°C
Showers turn to rain late morning, downpours and possible thunderstorms from afternoon. Strong, gusty northerlies change westerly overnight. High 25°C; 17°C
Showers, turn to rain afternoon with downpours and possible thunderstorms. Strong northerlies, change southwest overnight. High 24°C; Low 19°C
Few spots of rain, becoming persistent afternoon with heavy falls. Northerly gale, easing from afternoon. High 25°C; Low 15°C
Mostly cloudy, chance shower. Rain from evening as strong northeast turns strong or gale southwest. High 31°C; Low 9°C
Rain with heavy falls, easing evening. Winds changing gale southerly this morning, easing evening. High 22°C; Low 11°C
Rain, heavy at times, easing evening. Strong southeast turning southwest by evening. High 17°C; Low 9°C