Weather warning: Look what's on the way

Thermal imaging gives a dramatic picture of the storm as it moves on to Northland and Auckland. Colours show the amount of rain the stormclouds are bringing - black and white areas indicate the heaviest falls. Photo / Supplied

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Powerlines company Vector has warned of possible blackouts this weekend as heavy rain and strong winds lash the north and east of the North Island.

Forecasters say a subtropical low approaching from New Caledonia could bring power cuts and damage property.

Bad weather is expected from Northland to Waikato.

Wind gusts of up to 140km/h - strong enough to push trees on to powerlines - are forecast for Auckland.

Last night, the Far North was beginning to see some of the wet weather. At 7.30, Far North District councillor Colin Kitchen said it was raining at Whatuwhiwhi on the Karikari Peninsula and "starting to storm up a bit".

Weatherwatch.co.nz said light rain was falling across northern parts of Northland and winds at Cape Reinga were close to gale force.

Vector warned people in Wellsford, Warkworth, East Coast Bays, Whangaparaoa, the Clevedon coast and Waiheke to be prepared for power cuts, and said other areas could also be affected.

MetService weather ambassador Bob McDavitt compared the severity of the approaching storm to the lesser of two storms that flooded Northland in July last year.

The low-pressure system would stretch from New Caledonia to the top of New Zealand, he said.

The MetService said that although the centre of the low should pass to the north of the country, heavy rain and damaging winds would hit the upper North Island.

Civil Defence warned Aucklanders to keep an eye on the forecasts and prepare for severe weather between lunchtime today and lunchtime tomorrow.

The MetService expects up to 150mm of rain to fall in Northland, especially on the eastern hills from Whangarei north. Rodney District north of Warkworth,

Great Barrier Island, the Coromandel Peninsula and the Kaimai Ranges are likely to get up to 120mm of rain.

Gales are likely to accompany the drenching. Gusts of 120km/h to 140km/h are likely in higher parts of Northland, Auckland, Great Barrier Island, Coromandel Peninsula and the Hauraki Plains.

The MetService said the combination of heavy rain and strong winds was likely to make driving hazardous and lead to flooding, slips, rapidly rising streams and rivers and possible damage to trees and buildings.

WeatherWatch.co.nz head weather analyst Philip Duncan also warned of power cuts and property damage.

"We're not wanting to alarm people - this is a moderate storm - but people should be prepared for powercuts and the potential for some damage."

Mr Duncan said there was a high chance of flooding, slips and damage to trees in eastern parts of Northland, Coromandel and East Cape.

Auckland Civil Defence said people in low-lying areas that were prone to flooding should have a getaway kit of medication and other essential supplies ready in case they had to move higher ground.