SH1 is currently closed at Puhoi north of Auckland this morning after a massive slip blocked the road.
Motorists are being advised to avoid the area and detour on the alternate SH16.
Heavy rain and wild winds are lashing much of New Zealand, with Auckland commuters being urged to delay travel this morning to avoid the worst of the storm.
Niwa has warned that a month's worth of rain may fall in parts of the North Island and in the northern and eastern parts of the South Island.
A deep low and associated rain-bearing front are moving down the North Island, to encompass the whole country.
Severe weather warnings have been issued for most of the North Island and much of the south.
Waka Kotahi NZ Transport Agency is closely monitoring the weather.
MetService issued a strong wind warning for Auckland from 2am until 9am today, with gusts of up to 110 km/h forecast to strike during the morning rush hour.
Drivers of high-sided vehicles and motorcyclists were encouraged to avoid the harbour bridge while wind warnings are in place and use the Western Ring on State Highways 16 and 18.
Auckland Transport was warning of disruptions to bus services on the North Express and on services from Glenfield, Beach Haven and Takapuna.
Metservice's rain radar just before 6:30am. Photo / Metservice
Ferry passengers are also being told to expect potential disruptions and also asked to delay their travel if possible.
The harsh weather is the result of a deep low moving across New Zealand, bringing with it associated fronts which cause the conditions.
Between Coromandel and Bay of Plenty, people can expect winds approaching gale-force and up to 110mm of rain, with rates of 15mm per hour at times.
Flooding is likely for many parts across the Waikato region. This is due to the heavy rain falling on already saturated catchments.
River flooding along low-lying coastal areas may also be exacerbated over high tide periods for all Waikato region coasts. The regional council has asked residents to stay vigilant for localised flooding and slips caused by the high river and stream levels.
The wintry blast is being attributed to an "atmospheric river" snaking across the country. These long, thin filaments of atmospheric moisture are capable of carrying double the average flow of the Amazon River – or 200 times that of our largest river, the Clutha/Mata Au.
Around 40 atmospheric rivers make landfall here every year, with four or five classified as strong and usually hitting around summer.
Gisborne to Hawke's Bay can expect similar conditions, with heavy rain. And at the bottom of the North Island, Wellington is set to experience gale-force winds until at least Wednesday morning.
The west coast of the top of the South Island is also forecast to experience severe winds. They are expected to rise to a gale gusting at 140km/h.
The Tararua Ranges will be drenched by heavy rain and, across Cook Strait, Nelson and Marlborough districts will be battered by rain and wind.
Canterbury's high country is under a heavy snow and rain watch, with heavy rain expected to turn to snow above 400m.
Central Otago and the Lakes district can expect similar conditions.
Several roads have heavy snow watches in place between Tuesday and Wednesday. These are: Lindis Pass, the Crown Ranges, Arthur's Pass, Porter's Pass, and the Dunedin and Waitati Highway.
MetService Forecaster Aidan Pyselman said the system will likely move off to east of the South Island tomorrow.He said it will clear up around the North Island especially, but then another low will move in from the north on Friday morning.
