Bad weather is now hitting Northland, Coromandel Peninsula and Great Barrier Island and is also forecast to reach Marlborough and the North Canterbury coastline, from tomorrow morning.
The rainfall in Coromandel is getting heavier, with more to come.
Thames Valley Civil Defence controller Garry Towler said a total of 400 millimetres of rain is expected by 10pm - the equivalent of the total rainfall over the past week.
He said further road closures could be expected later today.
The State Highway on the eastern coast between Hikuai and Whitianga was likely to close, as well as State Highway 25 going into Thames.
Towler said the damage to roads was significant in a one in 20-year storm event.
MetService predicts the severe weather in the region will ease later this evening.
Several roads across Northland are now closed as Cyclone Hale continues to affect the region.
State Highway 15 between Loop Rd, Otaika and Mangatapere, south of Whangārei is closed due to flooding.
Kokupu Block Road is also closed due to flooding and police are advising motorists to avoid travel around Northland unless urgent.
Police say two vehicles that were stuck in flooding on Waiteitei Road in Wellsford have since made it out. There are no reports of injuries.
A heavy rain warning remains in place for the region till 7pm today.
More than 100 homes in Coromandel were without power earlier.
"We had quite a lot of impact last night," Towler told Morning Report.
The eastern seaboard has been most affected, he said, and it was highly likely the entire eastern seaboard would close after high tide, he said.
"We've got widespread flooding, we've got a number of slips all the way from Hikuai all the way up to Whitianga. Widespread phone and power outages as well.
"The impact is quite dramatic in terms of what is still to come but also we've got to keep this in context because we had over 400mm of rain last week and there's just no capacity to absorb some of this stuff."
In Whitianga 136 properties in the town of Whenuakite have been without electricity since 2am today. The network company was investigating the cause of the outage.
At 11am police advised residents to stay indoors and away from the coast as high tide was due at 11.15am.
Several roads in Thames-Coromandel district have been closed because of the storm.
As well as Coromandel, wide impact is also expected in Gisborne and Hawke's Bay as the weather front fans out across the island.
MetService issued severe weather warnings for Gisborne, Coromandel, Northland up to the Bay of Islands, Auckland including Great Barrier Island, and Hawke's Bay.
It forecast heavy rain, gale-force winds and storm surges. The rain is predicted to peak in most areas this afternoon.
It has also now added a heavy rain warning for Marlborough and the Canterbury coast from Cape Campbell to Kaikōura.
