Severe Thunder & Hailstorm Warnings Sweep Across parts of NZ

New Zealand experienced a dramatic shift in weather on Thursday as MetService issued a series of severe thunderstorm warnings and watches across large parts of the South Island and the central North Island. Intense weather systems brought torrential rain, large hail, frequent lightning and the threat of flooding, prompting authorities to urge residents to stay alert as conditions rapidly deteriorated.

South Island storms intensify

At 4.21pm, MetService released a severe thunderstorm warning for Waitaki and Dunedin City after radar detected strong storm cells near Waikouaiti, Hummock-between Middlemarch and Waikouaiti-and Hindon. Tracking northeast, these storms were forecast to reach Palmerston, Waikouaiti and Hummock by 4.45pm, before moving towards Palmerston, Waikouaiti and Moeraki by 5.15pm, according to reports quoted by Stuff.

“These thunderstorms are expected to be accompanied by torrential rain and large hail,” MetService warned. The alert highlighted the potential for hazardous driving conditions and damage to property, crops and vehicles.

Earlier in the afternoon, at 3.30pm, a separate severe thunderstorm warning had already been issued for Central Otago and Dunedin City. Radar imagery showed a thick band of heavy rain stretching from Alexandra to Dunedin, signalling the scale and intensity of the system sweeping eastward.

High-risk outlook for Canterbury and Otago

A thunderstorm outlook issued at 2.12pm placed South Canterbury and eastern Otago in a high-risk zone. Forecasters warned that hailstones could exceed 20mm in diameter, with a slight chance of small tornadoes forming under the volatile conditions.

In the South Island, the severe weather was driven by an upper cold trough interacting with northeasterly winds that later shifted southwest. This clash of air masses created ideal conditions for unstable, fast-developing thunderstorms.

Dunedin battered by lightning and flooding

Dunedin bore the brunt of the afternoon storms, experiencing intense thunder, vivid lightning and sudden downpours that overwhelmed drainage systems. Streets were left waterlogged, traffic slowed to a crawl, and surface flooding became widespread in low-lying areas.

Images shared with Stuff captured a lightning bolt striking as the storm approached central Dunedin, while MetService radar at 3.35pm confirmed the dense rain band moving over the city. The storms had passed through Middlemarch at 3.22pm and reached Dunedin shortly after 4pm.

MetService reiterated the dangers associated with the severe weather. “Torrential rain can cause surface and/or flash flooding about streams, gullies and urban areas, and make driving conditions extremely hazardous,” the agency said. Large hail, it added, could cause “significant damage to crops, orchards, vines, glasshouses and vehicles”.

Adding to the dramatic contrast, photos from Dunedin Airport earlier in the day showed frost still coating pavements, even as dark storm clouds gathered ominously on the horizon.

The severe weather watch remained in force until 9pm for the Canterbury Plains, Canterbury High Country, North Otago, Dunedin and Clutha. Forecasters warned that some storms could deliver 25–40mm of rain per hour, hail larger than 20mm, and a slight chance of small tornadoes, increasing the risks of flash flooding, slips and dangerous driving conditions.

Central North Island under watch

Shortly after 4pm, MetService expanded its alerts northward, issuing a severe thunderstorm watch for Waikato, Bay of Plenty, Rotorua, Taupō, Gisborne and Hawke’s Bay, effective until 10pm.

Slow-moving, isolated thunderstorms developed across inland areas of Rotorua, Bay of Plenty, Gisborne/Tairāwhiti, Hawke’s Bay and Taupō during the afternoon and evening. In parts of Waikato, Bay of Plenty, Rotorua and areas north and east of Taupō, some storms were expected to become severe, producing localised downpours of 25–40mm.

Warm temperatures combined with light winds in the North Island encouraged rapid cloud build-up, creating conditions ripe for heavy rain and hail.

Calmer conditions elsewhere

Not all regions were affected by the volatile weather. Auckland remained mostly fine, with only a chance of an afternoon shower in eastern areas. Wellington enjoyed settled conditions with winds easing later in the day, while Tauranga was largely fine despite the possibility of a heavy afternoon shower.

MetService said thunderstorm activity was expected to ease later in the evening, but warned residents to remain cautious as conditions could change quickly. The Indian Weekender will continue to provide updates as the situation develops.

FAQs

What areas were most affected by the severe storms?

South Canterbury, eastern Otago, Dunedin, Central Otago, and parts of the central North Island including Waikato and Bay of Plenty faced the highest risk.

What hazards did MetService warn about?

Torrential rain, flash flooding, large hail over 20mm, dangerous driving conditions, and a slight chance of small tornadoes.

How much rain was expected?

Some thunderstorms were forecast to produce 25–40mm of rain per hour in localised areas.

When were the warnings expected to ease?

Thunderstorm activity was expected to ease later in the evening, though watches remained in place until 9–10pm in some regions.