Thirteen people are still unaccounted for since Cyclone Gabrielle battered New Zealand, authorities say, as more heavy rain prompts evacuations on the country's North Island.

Gabrielle struck New Zealand on February 12, causing widespread devastation across the North Island, leaving at least 11 people dead and displacing thousands.

More than 6000 people were uncontactable following the cyclone as communications were knocked out in many areas - a number that has receded amid recovery efforts.

"Getting in touch with those remaining 13 remains a priority for police and we are working as fast as we can," New Zealand police said in a statement on Saturday.

In Hawke's Bay, one of the areas worst hit by Gabrielle, heavy rains overnight brought a renewed flood risk to the region on Saturday, with an evacuation order in place.

Homes in the Esk Valley had "been unoccupied since the cyclone, but an additional 26 households evacuated yesterday", Hawke's Bay Emergency Management Group said on Saturday.

About 680 kilometres north, in the town of Mangawhai in Northland, more than 200 people sheltered in camps on Friday night as landslips blocked roads, Radio New Zealand reported.

The wild weather also triggered flash floods and evacuation warnings in and around Auckland, the nation's largest city with a population of about 1.6 million.

New Zealand weather forecaster MetService said some of the heaviest rain was recorded in Auckland, with 155mm falls in the past 24 hours.

The forecaster had a heavy rain warning in place on Saturday for large swaths of the North Island's east coast, including Hawke's Bay.

"Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous," it said.

MetService said it was also "closely monitoring" a tropical low near Fiji that could turn into a tropical cyclone next week.