A landslide in Brynderwyn Hills damaged cars and blocked part of State Highway 1.
MetService warns of potential flash flooding and slips in affected areas, urging caution for motorists.
The tail of ex-tropical Cyclone Tam will deal out one last lash across the country today as many regions continue to clean up from its destructive impacts.
A severe thunderstorm watch has been issued for a large area of the central North Island, from Hawke’s Bay through Bay of Plenty.
Yesterday, a landslide in the Brynderwyn Hills badly damaged cars and blocked part of State Highway 1, as Auckland and Northland were slammed with heavy rain once again.
It came after days of torrential downpours and heavy winds after ex-tropical Cyclone Tam and secondary severe weather patterns washed over from Thursday.
MetService said there was a moderate risk of severe thunderstorms for Rotorua, inland Bay of Plenty, the southwest corner of Gisborne, Taupō, inland Hawke’s Bay and Taihape.
The storms were expected to be accompanied by localised downpours with rainfall 25 to 40mm/h and hail.
“A slow-moving area of low pressure affects the North Island today [Monday]. A warm moist air-mass and low level convergence are likely to generate showers and possible downpours,” MetService said.
“Rainfall of this intensity can cause surface and/or flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.”
Heavy rain warnings have lapsed for areas in the South Island as the rain eased but remnants of the storm are still proving painful for some.
State Highway 67 remains closed between Hector and Mokihinui, after flooding overnight, NZ Transport Agency said on X.
“Delay travel through the area.”
SH67 HECTOR TO MOKIHINUI - FLOODING - 5:55AM, MON 21 APR State Highway 67 is currently CLOSED between Hector and Mokihinui, following flooding overnight. Delay travel through the area. ^CS pic.twitter.com/0ePOmtzZgy
— NZ Transport Agency - Canterbury & West Coast (@nztacwc) April 20, 2025
The severe thunderstorm warning for Auckland was lifted at 7.16pm yesterday.
MetService meteorologist Alec Holden said the severe thunderstorms that cropped up around Auckland overnight could make an argument for the worst of the weather, but they did not make up the largest rainfall.
Strong winds and changeable weather left debris on Auckland's North Shore at Cheltenham Beach after Cyclone Tam. Photo / Alex Burton
He said the very edge of Cyclone Tam’s tail whipped up significant rainfall over the top of the South Island with areas such as Westport reporting surface flooding.
Holden said upper South Island areas would “still be under the influence” of Cyclone Tam today but it would start to lose steam throughout today and the rain would ease.
As the weather system crept towards the Hawke’s Bay there was potential for “sparks to fly”.
“There may be some localised thunderstorms, but they won’t be like we have seen in Auckland over the last couple of days.”
Yesterday, for the second day in a row, Aucklanders’ phones were pinged with an emergency alert from Auckland Emergency Management warning of severe weather arriving about 6.30pm.
“Torrential rain can cause surface and/or flash flooding and make driving conditions extremely hazardous,” the alert read.
Police said the Brynderwyns slip was between SH12 and Artillery Rd and motorists in the area were advised to drive with caution as the southbound lane was closed from debris.
“There were many large and small waterfalls coming down the banks from the top to the base of the Bryns,” the motorist said.
“[There was a] huge waterfall at one point about halfway down, which appeared to be going down a large grated drain.
