A Civil Defence emergency has been declared in the Nelson region as torrential rain batters the area, making driving treacherous and closing roads.
Nelson Tasman Civil Defence spokesman Chris Choat told NZ Newswire the emergency declaration had been made in the evening because emergency services were dealing with an increasing number of incidents and they needed greater powers to be able to deal with them.
He urged people to stay home and keep off the roads, many of which were affected by surface flooding.
One home in the suburb of Tahunanui has been evacuated after its deck and pool detached from the main house, and two tourists perched in a tree in the middle of a swollen Maitai River in Nelson were rescued by surf lifesavers.
The pair had wandered down to the river to get a closer look when they were caught out by rising waters and were forced to take refuge up a tree.
Video footage showed the surf lifesavers wading out to the pair with an inflatable boat in water that was up to one rescuer's chest and was flowing quickly.
Some houses along the river, which runs through the centre of Nelson, have been sandbagged as a precaution.
Several tonnes of falling soil from a cliff smashed into the side of a car on Rocks Road, the main road around the Nelson waterfront, and the driver escaped death, a witness told the Nelson Mail.
Surface flooding has made driving treacherous and closed roads around the city, Richmond and in Golden Bay.
The MetService says torrential downpours are expected to ease on late on Thursday morning.
Another 150mm to 300mm is likely in the Nelson ranges and a total of 500mm possible in some places.
NZN