Weather: Orange heavy rain warning for Northland, MetService monitoring tropical cyclone Vaianu

Heavy rain is continuing to batter Northland's east coast, with the Kāeo River threatening to flood across State Highway 10 north of the Bay of Islands.

High tide passed at 11am.

The wettest areas so far have been Kerikeri, Whakapara and Whangaroa, which have each recorded around 80mm of rain in the past 24 hours. MetService earlier warned up to 120mm could fall, with peak rates up to 40mm an hour.

In Punaruku, the area battered by the January storm, just over 50mm had fallen.

There were no reported power outages or highway closures, but Civil Defence was urging motorists to take extreme care as a subtropical low made its way south.

Northland Civil Defence earlier said roads and river levels were mostly stable, but there was a lot of surface water on roads and paddocks, especially in the east, and the ground was still saturated from previous downpours.

MetService cautioned of surface flooding, slips and difficult driving conditions.

Northland's orange heavy rain warning has been downgraded to a heavy rain watch until 6pm Tuesday, with MetService saying the storm was tracking south.

Next in the firing line was the western Bay of Plenty, where an orange heavy rain warning will be in place from midnight.

A strong wind watch remained in place for Northland until 5pm.

Much of the rest of the upper North Island remained under a heavy rain watch, including Auckland, Waikato, Coromandel and the eastern Bay of Plenty.

Forecasters expected the bad weather to reach the northern South Island by Wednesday evening. Heavy rain watches for late Tuesday were in place in parts of the north of the island.

Cyclone warning

Meanwhile, a tropical cyclone could potentially head towards New Zealand within the next week.

Two tropical cyclones were hovering over the South Pacific - Cyclone Maila in the Solomon Sea and Cyclone Vaianu to the east of Vanuatu.

MetService forecaster Louis Fernando said the Category 2 Cyclone Vaianu looked like it would intensify to a Category 3.

"Some of the models are indicating that perhaps towards the weekend the remnants at least of the cyclone could affect parts of the North Island."

Northland experienced heavy rains and flooding at the end of March and some parts are still recovering from the deluge.

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