Wild weather from ex-Tropical Cyclone Gabrielle has seen New Zealanders log 18,000 incidents of storm-related damage, according to Fire and Emergency NZ.
Deputy chief executive Steph Rotarangi told media on Tuesday afternoon calls from the Hawkes Bay area had "rapidly increased" though the day.
"As the cyclone tracks down the country, incidents are starting to come in from Taranaki and Manawatu-Wanganui," he said.
Ms Rotarangi said emergency authorities were still searching for a firefighter who was trapped in a landslide last night.
A national state of emergency has been declared in New Zealand for the third time in the country's history, as ex-Tropical Cyclone Gabrielle causes heavy downpours and strong winds.
Rainfall gauges on the north island recorded huge totals overnight, with Napier Airport on the country's east coast receiving 175.8 millimetres of rain in 24 hours — the second wettest day since 1950, according to the MetService.
At 5am (AEDT) ex-tropical Cyclone Gabrielle reached 996 hectopascals, and was moving at 10 kilometres per hour south-easterly over the Bay of Plenty.
Worst weather to pass by Wednesday
The ex-Tropical cyclone is expected to be north-east of Chatham Island by Wednesday, according to the MetService.
Severe weather warnings for strong wind, rain and swells are in place for large parts of the north island and the north-eastern part of the south island.
"Multiple roads are closed, there are so many power outages," the MetService's Lewis Ferris told News Breakfast.
Mr Ferris said Tuesday would bring the worst of the wild weather.
"We've just got to get through today," he said.
"As we head into Wednesday, there'll still be some severe weather lingering on the north-eastern coast of the south island.
"But getting through Wednesday and into Thursday, we're going to see a lot more settled weather."
New Zealand prime minister Chris Hipkins said the government would be focused on recovery and support for victims of the floods.
"We know that this won't be an overnight recovery, it's going to take a while," Mr Hipkins said.
"Some people will be displaced from their homes for an extended period … businesses will continue to feel the tail of this for some time and we'll need to support them through that as well."
Powerful storm
The ex-Tropical cyclone is expected to decrease in power as it travels south-east toward the Chatham Islands, according to Climate Prescience Limit director Nathanael Melia.
"One of the major warnings we have in place now is for the area around Auckland and the west coast of the northland," Dr Melia said.
"And that's the recirculation of the cyclone, as it moves eastwards off the coast, you've got all this strong wind whipping around behind it.
"But the rest of the country is moving into recovery and clean-up mode."
Dr Melia said the long La Niña was a major reason ex-Tropical Cyclone Gabrielle was so strong, in addition to a marine heatwave and climate change.
"The problem we have with Gabrielle is that it formed in the Coral Sea … and as it travelled down it's got caught up in the jetstream, which turbocharged [the system]."
