Weather: Cyclone Oma - Heavy rain set to hit Auckland, Northland, North Island on Friday and weekend

A "significant weather change" is heading for the country as several cold fronts move up the country bringing gale force winds, sharp temperature drops and heavy rainfall.

MetService is predicting Cyclone Oma will slide past the country but we're not out of the firing line.

Heavy rain, winds and storm surges from the cyclone have uprooted trees, destroyed homes and food crops in Torba and Sanma provinces in Vanuatu.

The Vanuatu Daily Post reported the main damage on all islands was coastal destruction.

Widespread damage was also reported in New Caledonia after power was knocked out for thousands of homes, while trees were felled and roads flooded.

The damaging weather system that pummeled parts of the Pacific, and the warm air sucked into it, is going to bring heavy rain to New Zealand today.

MetService lead forecaster Mark Todd said this morning the upper North Island was at greatest risk of heavy rainfalls from northern Auckland up to Northland.

"What we have is some very, very moist warm air sinking southward from the tropics later on today and into tomorrow."

A heavy rain warning was in place for Northland, with up to 100mm of rain expected by midnight.

That could spell trouble, with the National Institute of Water and Atmospheric Research warning that the rain combined with dry, concrete-like ground, there could be flooding due to excessive runoff

Similar rainfalls could affect northern Auckland from the afternoon and overnight.

"There is a significant weather change coming for many parts of the country - there are a couple of cold fronts coming in from the south, bringing in significantly colder air.

"We are going to see a drop in temperature in many areas. There are also going to be gale-force southerly winds in many places and risk of heavy falls in eastern areas of the North Island," Todd said.

Christchurch's high was 28C with an overnight low of 9C.

A heavy rain watch was in place for Auckland north of Orewa and the Tararua Range through to Saturday.

Fear of Flooding on Waiheke Island

Concern is mounting on Waiheke Island as the small community prepared for a barrage of wild weather that would likely overwhelm the island's drainage.

Healthy Waters contractors inspected more than 50 sites on Thursday and would be completing any maintenance needed by the end of business on Friday.

Manager Craig Mcilroy said the inspections were intended to identify issues with hotspots, such as inlets being blocked with vegetation or debris, and clear them before the weather hit.

Erua Rd and Tahi Rd in the Tawaipareira Stream catchment area were a concerning area.

Mcilroy said flooding at this location was common so Auckland Council was working towards a solution that could reduce future flooding.

Waiheke Local Board Chair Cath Handley said the community would need to pull together to get ready and respond if there was more water than the island's drainage could cope with.

"Since the last major storm in 2017 many fixes have been put in place by owners, Healthy Waters and Auckland Transport, while other locations are still working on solutions.

"Our land is so dry it's not going to mop this water up if it's a deluge, so we all need to be on alert and to look out for less-able neighbours. It's an anxious time for those who have been flooded before," Handley said.

Weekend Forecast

The forecast on Saturday showed the low over the upper North Island should move rapidly to the east - with rain expected in many places, especially in the north.

There was low confidence that rainfall would meet warning criteria from Coromandel Peninsula to East Cape.

On Sunday, an active trough should move northwards across central and northern New Zealand, bringing strong cold southerlies and showers.

There was low confidence of heavy rain on the east coast of both islands from North Canterbury to Gisborne.

"Also on Sunday, there is low confidence of severe southeast gales in Buller and northwest Nelson, and of southerly gales becoming severe from the Kaikoura Coast to Taranaki and northeastwards to East Cape."

Your Weather for Friday

Whangārei

: Rain, heavy at times, easing overnight. Northeasterlies strengthening.

High 23C Low 19C

Auckland: Cloudy, isolated showers. Rain setting in from late morning, possibly heavy from afternoon. Northeasterlies strengthening.

High 24C Low 19C

Tauranga: Cloudy. A few showers, turning to rain afternoon or evening. Northeasterlies strengthening.

High 25C Low 19C

Whanganui: Cloudy, chance shower. Northwest breezes.

High 25C Low 15C

Napier: Cloud thickening, possible evening shower. Northerlies.

High 30C 19C

Wellington: Cloudy with a few showers. Northerlies, strong for a time.

High 22C Low 15C

Christchurch: Fine at first then cloud increasing from afternoon. Northwesterlies change southerly in the afternoon.

High 28C Low 9C

Dunedin: Early rain, then fine apart from chance afternoon shower. Southwesterlies.

High 22C Low 10C