Flights to Gisborne tonight have been diverted, and residents living near Hikuwai and Waipaoa rivers are being alerted to flood warnings.
Multiple orange heavy rain warnings and an orange strong wind warning has been issued for the East Coast, while the city's emergency sewer valve has also been opened.
A rainy Gladstone Street in Gisborne. Photo: RNZ / Jimmy Ellingham
The first warning, to residents in the Tolaga Bay area, said flood-prone Hikuwai River was rising to flood levels.
It is now past the 10m mark.
A second warning has been issued to residents living along the Waipaoa River, which flows around the Gabrielle-stricken township of Te Karaka and across the Gisborne flats.
The warning says the river has now passed the 5m mark.
In Gisborne itself, the Waimata River had risen to 7.3m late on Tuesday, and was expected to peak in the early hours of the morning.
Flights from Auckland and Wellington to Gisborne on Tuesday night have been diverted, while the flights from Gisborne on Wednesday morning have been cancelled.
The Uawa Tolaga Bay Civil Defence manager said severe wind conditions were the worst he had seen in a long time.
Greg Shelton said high winds had downed trees and cut power to a lot of homes, as the region was hammered by severe weather.
A team of eight would work through the night and be relieved by a fresh group of 10 on Wednesday morning, he said.
"At the moment, these are probably the worst conditions, wind wise, I've seen for a long, long time.
"We're expecting a lot of damage from the wind, more than anything.
"I'd say in the morning we're going to be faced with some pretty ugly scenes."
Gisborne's emergency sewer valve has been opened due to fears of sewage overflowing back into homes and onto roads.
The Hikuwai River near Willow Flat has past the 10m mark. But its banks could handle up to 13 metres, Shelton said.
There were orange heavy rain warnings for Gisborne/Tai Rāwhiti about and south of Ruatoria and Hawke's Bay north and south of SH5.
An orange strong wind warning was also in place for Gisborne/Tai Rāwhiti and Hawke's Bay from Wairoa northwards, including Māhia Peninsula.
Severe gale southerlies could reach 120 km/h in exposed places, MetService said, with the strongest winds are expected in coastal places.
At 3pm, there was 44mm of rain recorded at Gisborne Airport, according to the Gisborne District Council.
The council said the city's wastewater system has been flooded with intense rain draining from residential homes.
Ground water levels had already very high due to rain that started at the weekend, and combined with more rain today has resulted in surface flooding finding its way into the sewer, it said.
To stop sewage overflowing back into homes and onto roads, the council had to release the excess water.
It opened the emergency sewer valve at Gladstone Road into the Turanganui River at 2.30pm.
Scour valves to the Taruheru River were opened at Palmerston Road and at Oak Street at 3pm and at Owen Road into the Waimata river at 3.08pm.
"We only open the valve when it's absolutely necessary and only in the areas with issues.
"The discharge is highly diluted with rain water, but still poses a health risk.
"We'll notify the Hauora Tairāwhiti Medical Officer of Health, water user and sports groups," the council said.
Temporary warning signs would be installed and the council advised no swimming, fishing or gathering shellfish in rivers and beaches until at least five days after the valves were closed and warning signs were removed.
Meanwhile, the council said Tiniroto Road was closing overnight at the bluffs from 7pm, with contractors scheduled to inspect it tomorrow at 7am to make a decision on reopening it.
SH35 was also closed between Anaura Road and Mata Road, Mangatuna.
There were also slips south of Tutira on State Highway Two from Wairoa to Napier.