Some 15,000 people have been left without electricity in Auckland, northern New Zealand, due to large-scale outages caused by powerful cyclone Gabrielle, local energy company Vector said on Sunday.

Gabrielle is expected to become one of the most serious storms to hit the country this century, and it is bearing serious repercussions for the Kiwis.

"Cyclone Gabrielle has started to make itself felt with widespread power outages, particularly in exposed areas across north Auckland," the energy firm said.

Gabrielle is a sub-tropical low-pressure system that downgraded from a Category 2 cyclone. It hit Norfolk Island on Saturday night, with its most destructive winds missing the island before going south toward New Zealand.

"Our crews are responding as quickly and safely as they can, given the current weather conditions. As of 7pm [06:00 GMT], around 15,000 customers were without power," Vector added in a statement. 

Moreover, the corporation said the expected deterioration of weather conditions could prompt further power outages through Monday.

Auckland, a city of 1.6 million, was in line for a "full trifecta" of heavy rain, strong winds, and storm surges, said New Zealander weather forecaster MetService spokesperson Georgina Griffith.

The Auckland Emergency Management called on the locals to prepare for the aftermath of the massive blackouts, including stocking up on essentials, such as food, batteries, blankets, and warm clothing, as well as staying updated by listening to the news on the radio.

Wind and rain were spreading from the country's north, with a 140 km per hour (87 miles per hour) wind gust reported on the country's North Island on Sunday afternoon, according to MetService.

Auckland Airport said airlines were announcing flight cancellations in light of the ongoing developments, calling on those who had booked flights to keep an eye out for updates.