Hawke's Bay storm: SH2 reopens between Napier and Wairoa

State Highway 2 between Napier and Wairoa has re-opened after days of closure because of flooding and slips - but drivers are warned of more heavy rain and strong winds tonight.

Waka Kotahi said this afternoon the coastal thoroughfare had re-opened, connecting Wairoa back to the south, but it urged drivers to continue to travel with care.

Heavy rain and strong wind warnings remain in place for the Wairoa district tonight.

Metservice said the area can expect a further 80mm to 100mm of rain, before it eases slightly on Saturday morning,

The Hawke's Bay area, excluding Wairoa, can expect a further 40mm to 70mm of rain.

A strong wind watch is in place until midnight tonight across coastal Tararua, Hawke's Bay and Gisborne.

Hawke's Bay Civil Defence is urging people who live near the water, to keep an eye on forecasts and warnings.

"If you are close to a river, stream, drain or other type of waterway – particularly if you live in Central Hawke's Bay and areas north of Napier – Eskdale, Tutira, and Wairoa – please keep up-to-date with the forecasts and be prepared to evacuate.

"Keep your emergency grab bag near.

"While the forecast is not as bad as it was [Wednesday], things can change quickly.
If you feel you, your family and/or your property are at risk, leave immediately and contact emergency services on 111."

Flooded fields on State Highway 2 the day after torrential rain hit the East Cape. Photo / Neil Reid

Niwa says torrential rain across the country this week has set a new national rainfall record.

Rainfall of 103mm recorded near Whangārei on Monday morning was a new hourly rainfall record for a low elevation station, it said.

A low-pressure system in the Tasman Sea was "siphoning moisture" from the wet and humid tropics into the northern North Island, Niwa principal scientist Chris Brandolino said.

"Around 3000 lightning strikes were observed in Northland and immediate offshore waters on Monday morning; this thunderstorm activity increased the rate of rainfall.

"Ongoing marine heatwave conditions around New Zealand may have also contributed to the heavy rainfall."

Brandolino said the current weather system had been particularly slow-moving because it had been blocked by an area of high pressure to the south-east.

He said it was a result of climate change.

"A warming planet means that we expect to see more extreme weather events like this.

"In the future, it's likely such events will become even more common and more extreme."