About 25,000 homes and businesses are without power after an "unplanned outage", Transpower says, with wild weather in the upper North Island the prime suspect.
Transpower says electricity was lost to the Auckland suburb Warkworth, as well as northern areas Wellsford, Kaiwaka, Maungaturoto, Ruawai and Mangawhai at about 3:30pm.
The outage occurred thanks to "a tripping of our double circuit line from Henderson", and crews were dispatched to assess the fault late on Wednesday afternoon.
The outage comes after severe weather conditions, including heavy rain, blustery gales and hail, struck across the North Island earlier in the day - however Transpower is reluctant to attribute it to bad weather until a full investigation has been undertaken.
In a Facebook post, Transpower revealed one of the two tripped circuits had now been restored, with electricity supply expected to return to affected areas within the hour.
However it wouldn't rule out further outages later on Wednesday if severe weather conditions persisted.
"Our work now is to find out what happened in this case, to help prevent [it] happening again," it said. "Thanks for your patience and understanding, and thanks also to our crews in getting out in this terrible weather."
On Tuesday, power company Vector told Auckland to brace for widespread power cuts ahead of forecasted strong winds that it said could cause "gale surges, thunderstorms and localised tornadoes".
While the more extreme weather conditions didn't eventuate, gusts in Auckland brought a few branches down, cutting power.
MetService says the current intense showery conditions that brought a hailstorm to parts of west Auckland earlier in the afternoon are expected to ease on Wednesday night.
"We're forecasting a few less intense showers to hang around into Thursday morning but they should clear as the day progresses."
A wind warning is in place for Northland, Great Barrier Island, Coromandel, Waikato, Waitomo, Auckland and parts of the Bay of Plenty.
Weather Watch says there will be a surge of windy weather moving into the upper North Island. Already gusts in Auckland have brought a few branches down, cutting power.
