A local state of emergency has been declared along the South Island's West Coast after strong winds and heavy rain pummelled the area.
The Waiho River in Franz Josef breached its banks, forcing nearly 200 people to evacuate the town's Scenic Circle Hotel, Top Ten Holiday Park and Westwood Lodge.
Despite the rain now coming to a halt, Andy Thompson from Westland District Council says there's been very fast-flowing water over the riverbanks.
"Had reports of very fast flowing water, we've had reports of cars being pushed around and tossed around into the carparks. There's damage to the Scenic Circle hotel, it's been inundated with water," he said.
He says nobody has been left in the welfare centre -- with Red Cross staff now manning that.
Mr Thompson says stopbanks are still being rebuilt, and it is going to take some time before they can divert the river.
He said they are trying to shore up a stopbank slightly above the breach so it doesn't get worse, but they are no longer trying to stop the water going through to a nearby hotel, as it is already significantly water-damaged.
Mr Thompson says he has seen water literally flowing through the hotel, high enough to break windows.
The access road to the sewerage ponds has been wiped out, as have the sewerage ponds.
While the town sewerage system is still working, when the sewage reaches the end of the pipe it's currently going into the river, because the oxidation ponds have been destroyed by the flood.
He says the town itself is very much under control -- but the main issue is a boil water notice, and a portion of the town is without reticulated water.
Southern fire communications spokesperson Brent Dunn says crews were kept busy.
"We had the Franz Josef fire brigade out last night assisting with some flooding in Franz Josef itself."
Dozens of people have been put in emergency housing in the town, while others have chosen to leave the area.
"About 80 of them were housed in Franz Josef overnight in a local hall, with the local Civil Defence volunteers and Red Cross looking after them," says Mr Thompson.
"A large number of them self-evacuated north because the road was shut -- they couldn't go south."
Mr Thompson says 138mm of rain fell in the four hours between 11pm and 3am.
Gale-force winds are battering the top of the North Island too. Thousands of homes across Auckland are without power this morning.
Northern fire crews and police responded to more than 90 weather-related calls, from trees on powerlines to trampolines on roofs.
Severe weather conditions are expected to continue across the Auckland for much of today, but MetService meteorologist Georgina Griffiths says Kiwis can rest assured the Easter weekend will be mostly fine country-wide.
"Heading for a pretty decent long weekend: An easing trend, it looks pretty good, there’s some flies in the ointment, a bit of cloud, a few showers around for the North Island."
"Overall a fairly settled Easter break, which is great news for the Easter Bunny."
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