Thunderstorms in Northland have cut power briefly to some areas and forced a flight to return to Auckland, with a flood warning in place for Kaeo and Ngunguru.
Civil Defence in Northland warned there could be flooding today around Kaeo in the Far North and on the Ngunguru Road, north-east of Whangarei.
MetService, which has a heavy rain warning in place for Northland, Coromandel Peninsula and Bay of Plenty, was expecting continued rainfall in Northland through to Saturday morning.
Civil Defence said people should be aware of localised flooding and check conditions before they set out.
The forecast was for 180 to 240mm of rain, especially in the east, with peak intensities up to 50mm per hour in thunderstorms.
The Kaeo River in the Far North was likely to breach its banks this evening but residents did not believe it would cause major flooding.
The river often flooded across State Higway 10 after heavy rain, temporarily closing a couple of local roads.
Garage owner John Owens, who lives nearby, said the water was likely to go down again quickly once high tide, due about 6pm, passed.
He said the river was not as backed up as it had been in some past floods, because the rain had been very localised and some parts of the catchment including Whangaroa have had very little.
Blasts of thunder and lightning rocked Whangarei this afternoon - rattling windows and setting off car alarms.
It was muggy on the ground, though, with overnight temperatures around 20°C and humidity near 100 percent.
Flight NZ8678 to Kerikeri was struck by lightning and forced to turn back to Auckland, where it landed about 2.20pm. The DH3 plane was being checked by engineers and the passengers moved to alternative services.
The power outage earlier today affected 1300 households, most for about 15 minutes. The areas affected were Gumtown Road, Houto, Kara, Kerehunga Road, Knight Road, Kokopu, McKinley Road, Pakotai, Parakao, Pipiwai, Poroti, Purua, Ruatangata West, Titoki, Twin Bridges, Wairua, Wharekohe, Whatitiri.
Arborists were working to remove bamboo from 33kV and 11kV lines at Poroti.
Police said there had been at least eight crashes in Northland in 24 hours, most of them caused by drivers following too closely on slippery roads.
Some Whangarei school buses were unable to run this afternoon because of flooded coastal roads, stranding students in town.
Halvorson Road between Whangarei and Whananaki was one of those affected. A local woman told RNZ her children and others were were staying in town overnight with friends and relatives.
Most campers on popular beaches north of Whangarei have packed up and left because of the weather and further predictions of heavy rain.
'Several hundred' Auckland homes without power
Earlier today, strong winds also cut power to several hundred homes in Auckland.
Lines company Vector said about 640 homes in Wellsford, north of the city, and 30 homes on Waiheke Island (where 18000 homes were earlier disconnected) were without power.
The strong winds come after downpours caused flooding and slips from South Auckland to the Coromandel Peninsula.
Civil Defence urged householders to prepare for what could be a rugged couple of days.
MetService said easterly gales were hitting exposed parts of Auckland from Whangaparoa Peninsula northwards, Great Barrier Island, Coromandel Peninsula and Waikato.
'The winds are really strong'
Meteorologist Peter Little said in exposed areas, such as Northland and Whangaparoa, there had been gusts around 95km/h.
Auckland was more sheltered, but wind gusts reached 65km/h on the Harbour Bridge.
"The winds are really strong, and are certainly gale force."