A red heavy rain warning has been issued as a significant weather event bears down on the upper North Island.

A deep sub-tropical low approaching New Zealand will bring heavy rain and strong northeast winds for Northland, Auckland, Coromandel and Bay of Plenty from late today through tomorrow and Friday.

“This will be an impactful multi-hazard event,” MetService warned.

A red heavy rain warning has been issued for Northland, east of Kaikohe from Doubtless Bay to Whangarei, from 4pm today to 4am Friday, with MetService warning that dangerous river conditions, significant flooding and slips could bring a threat to life.

MetService said to expect 270mm to 320mm of rain with peak falls of 25mm/h to 40 mm/h and possibly greater from Thursday afternoon through to early Friday morning.

The remainder of Northland, Auckland and Great Barrier Island have had orange warnings for wind and rain issued.

Meteorologist Silvia Martino told the Herald rain would start spreading south into Northland this afternoon.

“The rain starts to get heavy in the evening and it really is a long period of heavy rain for them,” she said, warning of consistent rain “for a couple of days”.

MetService said the heaviest rain was likely in the upper North Island, especially from Northland to western Bay of Plenty.

“Downpours, flooding, and slips are possible on Thursday and Friday.”

Heavy rain warnings are also forecast to come into force for Great Barrier Island and the Coromandel Peninsula from early tomorrow morning until Friday night.

Martino said the rain would begin to move across Auckland today; however, the heaviest rain would drench the city tomorrow and into Friday.

The wet weather will continue to spread southward tomorrow, with the Coromandel and Bay of Plenty set to be drenched in the morning, Martino said.

An orange heavy rain warning comes into effect for the remainder of Northland, not under the red warning, from 4pm today until 4am on Friday.

Weather watches and warnings issued across the country. Photo / MetService

An orange strong wind warning has been issued for Auckland and Great Barrier Island from 8am tomorrow until 1am on Friday.

Bay of Plenty west of Whakatane will be under an orange rain warning from 9am tomorrow until 3am on Saturday.

Several other parts of the North Island, including Waikato and Taranaki, have had wind and rain watches issued.

In the South Island, rain warnings for Tasman west of Motueka as well as Richmond and Bryant Ranges will come into effect tomorrow, while several watches have been issued across the island.

Powerful winds were forecast to bring heavy swells to coastal areas.

“Expect heavy swells with heights exceeding 4m to affect coastal areas of the North Island from Wednesday night,” MetService said.

“Later in the week, big waves will affect the South Island, with swell heights possibly exceeding 6m, especially in the western coastal areas.”

NZ Transport Agency Waka Kotahi (NZTA) warned motorists of possible disruptions to travel on the Auckland Harbour Bridge as high winds are forecast between 9pm tonight and 9am Friday.

Winds “may force lane closures and additional short periods of full closure to ensure safety”, said NZTA.

The strongest gusts, some potentially blowing at 120km/h, are expected to hit overnight on Thursday.

The transport authority advised drivers of high-sided vehicles and motorcyclists to avoid the bridge and use the western ring route on State Highways 16 and 18.

Civil Defence Northland said residents should prepare for the incoming weather.

Recommended action included:

• Clear drains and gutters.
• Secure loose outdoor items.
• Move valuables and vehicles away from flood-prone areas.
• Relocate stock from low-lying land and bring pets indoors.
• Have essential supplies ready in case of power outages or road closures.
• Have a grab bag and evacuation plan ready.
• Not to enter floodwaters.
• Avoid unnecessary travel.
• Be prepared to self evacuate.
• Be aware of landslide risks, and keep well away from areas that have recently been affected by slips or landslides.
• To call 111 if you, family or property are at immediate risk.

The organisation said it was monitoring the situation and positioning resources across the region so it could respond effectively if needed.

NZTA Northland journey manager Kingston Brands said Northland motorists should take care on the roads.

“Strong winds and prolonged rain mean drivers should expect possible disruption and plan accordingly”.

Brands said Whakapara, Kaeo, and Rangiahua are common spots for surface flooding where drivers should take extra care travelling through.

“We are urging people to drive to the conditions and consider delaying non‑essential travel during heavy rain. Do not drive through floodwater and follow all road signs and instructions, noting ongoing road works will also be on parts of the state highway network.”