Winds were starting to strengthen to up to 130km/h on the east coast of the South Island and more than 150cm of snow could fall in some areas overnight, Mr Corbett said.
The polar blast is already causing strong winds and heavy showers on the North Island but it is expected to worsen significantly tonight.
"As we get to about nine o'clock to midnight tonight, somebody is almost like opening the flood gates through Cook Strait and whoosh, up it will come, barrelling in. That will bring the stronger winds into Wellington," Mr Corbett said.
At Sawyers Bay, near Dunedin, a woman was rescued from her home after a landslip trapped her inside and brought a tree down on her car this morning.
SEWERAGE ISSUES
Several residents at Leeston, south of Christchurch, woke to flooding from heavy overnight rain, which has also affected the town's sewerage system.
Selwyn District Council has asked Leeston residents to minimise toilet flushing while the sewerage system is being repaired.
A council spokeswoman said staff were sandbagging some properties and clearing blocked drains and roads but the water levels appeared to be receding. The flooding has also caused Ellesmere College and Leeston Consolidated School to close today.
POWER
Electricity companies have warned of possible power cuts, emergency refuge centres have been set up, and shoppers are being urged to stock up but refrain from panic buying.
Power was cut to about 3000 people in the Mackenzie District this morning as the area experienced snowfalls of about half a metre.
TRANSPORT
"At this stage snow ploughs are out on the State Highways, and the snow plough has been around the township here in Fairlie and they are working their way out to rural areas now," Mackenzie Civil Defence emergency management officer Ray Gardner said.
Senior Constable Craig Bennett said there had been some traffic accidents in North Otago.
"And then I've had a farmer who was out feeding his sheep and an embankment in the snow has given way and pushed his vehicle into the middle of the Hakataramea River. So he had a cold wake-up and we had to get a tractor to extract him," Mr Bennett said.
Mount Cook Airlines, a subsidiary of Air New Zealand, has suspended all of its ATR operations into and out of Queenstown Airport as a result of worsening weather conditions.
Air New Zealand jet services continue to operate in Queenstown.
"Unfavourable weather conditions have caused some late running services across other domestic ports, but most Air New Zealand services are operating as scheduled," a spokesman said.
SEVERE WEATHER WARNING
A severe weather warning remains in place for most of the country.
MetService warns of severe gales about western and northern parts of the South Island, Wellington, Northland and Auckland.
There is also a warning for heavy snow and rain for the south and east of the South Island.
"People should be aware that snowfalls are likely to cause widespread disruption to traffic, especially about alpine passes and higher level roads. Damaging winds are likely to bring down trees and powerlines, make driving dangerous for high sided vehicles and motorcycles, and can cause damage to some structures."
WILL THERE BE SNOW IN AUCKLAND?
WeatherWatch head analyst Philip Duncan said flurries of snow may be seen at lower altitudes in Auckland, where there is a risk of hail and isolated thunder tomorrow.
"While the snow level will likely be 500 metres-plus, which is higher than the peaks in Auckland, downpours may be big enough to blow snow flurries down onto the tops of the Waitakeres, Hunuas and possibly Bombays,'' he said.
