Weather: Thunderstorms, torrential downpours for Northland; MetService issues alerts for Auckland, Coromandel, Gisborne

Up to 6cm of rain an hour and severe thunderstorms that are forecast to begin mid-afternoon have prompted warnings of flash flooding and slips across the top of the North Island.

Motorists have also been warned, with the New Zealand Transport Agency Waka Kotahi (NZTA) telling them to keep a close eye on state highways: “Please expect short-notice closures”.

MetService has issued a 19-hour orange heavy-rain warning for Northland as a subtropical low and preceding fronts move slowly southwards across the top of the country. It will come into place at 3pm and lapse at 10am tomorrow.

“Expect up to 90 to 120mm of rain, mostly in the north and east,” MetService said, adding that “25 to 60mm an hour possible in localised thunderstorms and downpours overnight”.

⚠ Severe Weather Warnings and Watches issued 20th January 2025

⚠ Northland and the Coromandel Peninsula have been upgraded to 🟠Heavy Rain Warnings🟠

Full details: https://t.co/qHyE5zzql5@AklCouncil @NRCexpress @OurCoromandel @NZCDEM @nztamain pic.twitter.com/ozcCvFV0BH

— MetService (@MetService) January 19, 2025

“Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible,” the forecaster said.

“Clear your drains and gutters to prepare for heavy rain. Avoid low-lying areas and drive cautiously.”

A severe thunderstorm watch coincides with the rain warning for Northland.

MetService said: “A band of heavy rain with embedded thunderstorms is expected to move southwards over Northland overnight.”

An orange heavy-rain warning will also come into effect for the Coromandel Peninsula from 6am to 9pm on Tuesday, with downpours expected in the morning and early afternoon with possible thunderstorms, MetService said.

MetService has also issued heavy rain watches for Auckland, Great Barrier Island, and Gisborne north of Tolaga Bay. These are in force from 4am until 9am on Wednesday.

🌧️ Wet & windy for the upper North Island 🌬️

An intense low brings easterly gales & heavy rain from Monday, with possible thunderstorms & localised downpours.

Meanwhile, the South Island stays settled early in the week before a front brings showers from Thursday. pic.twitter.com/XiigXgbIX1

— NIWA Weather (@NiwaWeather) January 19, 2025

Auckland, Great Barrier Island and the Coromandel Peninsula will also be under a strong wind watch tonight, coming into effect from 1am and lasting to midday.

‘Take extra care’ - Northland Civil Defence

Northland’s Civil Defence group has warned people to “keep an eye on the weather and take extra care” ahead of the forecast 19 hours of torrential rain.

“We will continue to monitor this weather system as it passes through,” the group said.

The NZTA said high-sided vehicles and motorcyclists should take “extreme care”.

“It’s really important to drive to the conditions, adjust your speed and following distance when you need to and be alert for the possibility of surface flooding and debris on the road.”

Meanwhile, Auckland has a mostly cloudy forecast with scattered rain predicted to ease to isolated showers. The daily high is tipped to reach 25C before falling to 22C tomorrow.

The rest of the country south of the Central Plateau was expected to miss the downpours and thunder.

The National Institute of Water and Atmospheric Research (Niwa) said the South Island’s weather would remain settled early this week before a front brought showers from Thursday.

Raphael Franks is an Auckland-based reporter who covers breaking news. He joined the Herald as a Te Rito cadet in 2022.

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