Severe thunderstorm watch for top of North Island, heavy rain brings new flood threat

Thunderstorm and heavy rain alerts have been extended for the top of the North Island as tropically-charged moist air brings a renewed threat of flooding for the second weekend in a row.

The rain has arrived in Northland with the region under a severe thunderstorm watch from 10pm today until 3pm on Sunday. Thunderstorms are also possible for Auckland, Coromandel Peninsula, Bay of Plenty and Gisborne.

A heavy rain watch came into force this morning and initially expected to last for 28 hours. It was revised this evening spanning from 8pm until 3pm tomorrow. Heavy falls with thunderstorms and downpours north of Kaikohe are expected to drift south overnight.

“There is a lot of uncertainty with respect to the amounts and distribution of significant heavy rain in Northland,” MetService warned, noting possibilities of flash flooding, surface flooding and challenging driving visibility in heavy rain.

Aucklanders can expect showers overnight and tomorrow, with periods of rain that may be heavy and laced with thunderstorms.

🟡🌧️The Heavy Rain Watch for Northland has been updated,
valid to 1 pm Sunday.

🟡 ⛈️A Severe Thunderstorm Watch has been issued for Northland from Dargaville to Whangarei north, valid from 1pm tonight to 1pm Sunday.https://t.co/qHyE5zzql5https://t.co/GZIq9J48pw… pic.twitter.com/nS9Ig4fsO9

— MetService (@MetService) April 25, 2025

MetService meteorologist Sarah Haddon said warm, moist air is being pulled across the country over the next few days by a low-pressure system in the north Tasman Sea.

“The most action is expected over the upper North Island, with a heavy rain watch as well as severe thunderstorm watch currently in place for Northland until 1pm Sunday,” she said before the watch was revised to end at 3pm.

“There is also a moderate risk of thunderstorms, with a low risk of downpours, for Auckland all day tomorrow, and this risk continues more broadly for the upper North Island into Monday.”

Kia ora Aucklanders, @MetService have released their thunderstorm risk chart for Sunday 27 April. Please be sure to keep up with the latest weather information. https://t.co/XRNaweYya5

— Auckland Emergency Management (AEM) (@AucklandCDEM) April 26, 2025

The latest MetService thunderstorm risk suggests a moderate threat of thunderstorms in the far north of Northland, north of Kaitāia to Bay of Islands, as well as heavy rain with intensities of 10-25mm per hour.

There is a moderate risk of thunderstorms spreading south over Northland, reaching Dargaville to Whangārei around midnight. There is also a low risk of thunderstorms over Auckland and the northern Coromandel Peninsula.

Niwa also said “uncertainty remains in the forecast” and there is the potential that the Far North District could receive moderate to heavy rainfall on Saturday and Sunday.

“A plume of moisture north of NZ will be the culprit. If it stays farther north, rainfall amounts will be lower,” Niwa said.

The top of the North Island was battered as Cyclone Tam slowly rolled over the country last week.

More than 20 Far North homes are still without power a week after the ex-tropical cyclone first struck the region.

Jaime Lyth is a multimedia journalist for the New Zealand Herald, focusing on crime and breaking news. Lyth began working under the NZ Herald masthead in 2021 as a reporter for the Northern Advocate in Whangārei.