Residents of Pahiatua have lost belongings, including a child's crib, to flooding, while others were "shocked" when they woke to find their homes completely surrounded by water.
Heavy rain overnight left several streets in the Tararua District town under water, and the council said about two dozen properties were affected.
By Sunday afternoon the flooding had largely receded, although some yards were still submerged.
Follow RNZ's live coverage of the wild weather here.
Huxley Street resident Sarah Popata said the water surrounding her house had gone down, but she was drying out her kitchen, which leaked during the downpour.
About two dozen homes were affected by the flooding. Photo: Supplied/ Luke Chandler
"The flood got into my house through the roof. My kitchen carpet was all wet and we had to put out pots last night to try and grab the rain
"The neighbours have brought me over a dehumidifier to help... It was a little bit of a mess," she said.
She hoped her landlords had insurance.
Around the corner on Wilson Street, residents said floodwaters were deep on Sunday morning before they receded when the rain stopped. But by the afternoon the water was on the rise again, and Downer workers were pumping it into drains.
Some people's belongings were destroyed by the floodwater. Photo: Supplied/ Luke Chandler
Natasha Figgess said when she woke at 6.50am the water was about halfway up to her house on her lawn.
Over the road it was higher. She said she was not too worried about the prospect of more rain.
Downer NZ traffic management worker Mike Fiti was going door-to-door on the street.
"We're just letting people know that there's an evacuation site down at the hall and just giving them some numbers so they can call, so if they need help they know what to do.
"They're pretty shocked from this morning at how high the water got, but the residents here are holding up in pretty good spirit."
Mike Fiti of Downer was going door-to-door. Photo: RNZ/ Jimmy Ellingham
A woman who lives on Huxley Street said she woke in the morning to see her house surrounded by water, which was scary, especially with her grandchild staying.
She and her husband's storage shed was flooded, so they had lost a lawn mower, golf clubs and their grandchild's crib.
Heavy rain warnings remained in place for the Tararua Range until 10pm.
The town's stormwater system reached capacity about 5am in the downpour, and earlier, Tararua mayor Tracey Collis asked people to avoid travel in or near the town, with a number of roads closed.
The Mangatainoka River was very high on Sunday. Photo: Supplied / Sam Te Tau
Resident Sam Te Tau said he had not seen Mangatainoka River run this high in more than seven years of living in the area.
The town's ageing infrastructure would struggle to clear the floodwaters if heavy rain continued to fall, he said.
"Our drainage systems here are quite old in the town, so they are often slow to clear the water.
"Where the flood waters are quite high, I can't see them draining off quickly."