Weather: Thunderstorm warning in North Island, downpours bring risk of flash flooding

• Severe thunderstorms and heavy rain are expected across the North Island, prompting weather warnings
• Auckland faces severe thunderstorm conditions with gusts up to 80km/h and potential flash flooding
• The South Island may experience snowstorms and heavy rain, impacting travel and safety conditions

Severe thunderstorms are forecast to strike the top of the North Island overnight, and squally downpours are bringing threats of flash flooding.

Millions of New Zealanders are under weather warnings and watches tonight after MetService issued a swathe of alerts for the South and North Islands.

Meanwhile, in the South Island, snowstorms are possible this evening, along with more heavy rain and strong winds.

Auckland is under a severe thunderstorm watch for eight hours from 8pm today. Winds could gust up to 80km/h in parts of the city this afternoon. Heavy rain was forecast to linger until tomorrow morning before turning fine.

MetService issued severe weather alerts for Northland, Auckland, Coromandel and the Bay of Plenty this morning, active for eight hours from 8pm today. Flash flooding, landslides, and dangerous driving conditions are possible, the forecaster warned.

Heavy Rain is possible for many areas of the country on Wed and Thu, with strong winds for the North Island and possible heavy snow for inland Otago

Warnings and Watches have been updated, with new areas added

Head to https://t.co/qHyE5zzql5 for full details pic.twitter.com/Qbb9kz7A7q

— MetService (@MetService) October 1, 2024

The storm-battered Gisborne region, north of Ruatōria, had its severe weather alert upgraded to an orange heavy rain warning earlier today. Up to 100mm of rain may fall in 18 hours.

Gusts up to 110km/h are also possible in these regions, as well as in Gisborne and Rotorua. These winds could down powerlines, trees and any loose structures. The Bay of Plenty Civil Defence group has already warned residents to take precautions.

Intense downpours began hitting the south of the country early this morning, with snowstorms expected later.

North Otago, Dunedin, Clutha, Southland and the West Coast are also under heavy rain warnings and watches. Tasman northwest of Motueka, the Richmond and Bryant ranges and Mt Taranaki are under an orange heavy rain warning until 6am tomorrow.

Heavy rain will impact the west & top, as well as the southeast, parts of the South Island.

On Thursday, another round of rain is forecast for eastern Otago/Southland.

Places like Dunedin & Balclutha may see twice their normal Oct rainfall in 2-3 days.

Flooding is a concern. pic.twitter.com/acvGRVaKkr

— NIWA Weather (@NiwaWeather) October 1, 2024

Road snowfall warnings are in place from 9am today at the earliest for Crown Range Rd, Milord Rd (State Highway 94), Lindis Pass (SH8) and Haast Pass (SH6). These should all lapse by 3am on Thursday.

Snow is possible down to 500m in Otago and South Canterbury on Thursday, when a mass of cold air passes over the South Island.

MetService meteorologist Lewis Ferris said it was “a bad start for the first week of the school holidays”.

Ferris said the severe weather is brought about by a low-pressure system approaching from the Tasman Sea, which drags some warm and humid air across New Zealand’s shores.

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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