North Islanders are being warned to expect a wild night, with heavy rain and strong winds forecast.
Fire and Emergency have had six weather-related callouts across the upper North Island since 6pm, northern communications shift manager Daniel Nicholson told Newshub.
Most of the incidents were due to strong winds, and emergency services were bracing for worsening weather later on Monday night, he said.
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Vector said there had been no significant outages so far, but extra crews were on standby in preparation.
"Strong wind gusts have the potential to damage power lines directly or cause vegetation and debris to blow into lines," said Marko Simunac, Vector's head of network field services. "Cars colliding with power poles in the wet is also a possibility in this type of weather."
Simunac said if weather caused power lines to come down, Vector would shut down power remotely until the crew could arrive on site.
"As always, our objective is to restore power as quickly as possible while ensuring the safety of our crews and the public."
The weather comes as a deep low moves over the north Tasman Sea, heading towards Northland on Monday evening before moving southeastwards across the upper North Island on Tuesday, according to the Met Service.
The heaviest rain is forecast in Northland, the Coromandel Peninsula, Waikato and western Bay of Plenty.
Heavy rain warnings are in place in Northland until 6am on Tuesday, in the Coromandel Peninsula until 11pm Tuesday and in Gisborne from Tokomaru Bay northwards from 4am on Tuesday until 6am on Wednesday.
Strong wind warnings are in place in Auckland, Great Barrier Island, Coromandel Peninsula, Waikato and western Bay of Plenty.
The NZTA was warning motorists in Auckland and Northland to be extra cautious on the roads.
The low is expected to affect parts of the North Island until early Wednesday.
Meanwhile, another low is forecast to begin moving over the South Island later in the week.