Two thirds of the country is expected to be hit by severe weather today.
Around 20 weather warnings are in place for heavy rain and strong wind.
WeatherWatch head analyst Philip Duncan says central parts of the country, especially the South Island, can expect heavy rain on both coasts.
He says the low out in the Tasman will fizzle out later today and the energy will be transferred to the East Coast.
Mr Duncan says a new low will form off the Canterbury coastline and deepen very quickly.
He says it's a bit of a double whammy with both coastlines getting severe weather.
It's a blustery day out Auckland's Hauraki Gulf and boaties seemed to have heeded the warning to stay home.
Average winds are 40 knots, and peaks of 56 knots have been recorded at Tiritiri Matangi Island.
Coastguard says one boat needed a jump-start at Waiheke Island, and has since made it back safely to Half Moon Bay.
There have been a handful of other incidents but most people have decided not to go out on the water today.
Fire crews in northern parts of the country are dealing with a spate of weather-related problems.
They've been called out four times during the morning to deal with trees brought down onto roads.
One was in Kerikeri, another was at Ngatea and there have been two in Auckland.
Several South Island rivers have peaked but the threat of more rain means they're still being closely watched.
Grey District Civil Defence says the Waiho and Hokitika Rivers peaked a couple of hours ago and the Grey River is below first alarm level.
Water levels in the Buller River are also at a plateau, but a spokesman says because it has a massive catchment the river can peak and then come back up again.
A large landslip has closed Milford Road in the South Island.
It's the only road into Milford Sound, and police say huge rocks have crashed down onto it.
The Transport Agency is reporting surface flooding on State Highhway 73 between Otira and Kumara.
There are also delays on State Highway 6 from Haast to Hawea because of a slip south of Makarora.
Photo: Rock slide at Milford (Supplied)