Cyclone Vaianu: Inside MetService’s forecasting – agency defends ‘life-saving’ calls amid weather ‘warning fatigue’ fears

“I stand by my comments that there is an over-enthusiasm to reach for the tool of declaring a state of emergency,” he wrote in the Hawkes Bay Today, after earlier describing it as “woke”.

Newstalk ZB host Nick Mills raised similar concerns, warning of a potential “boy who cried wolf” effect.

Along Ōhope Beach itself, views were mostly thankful. Residents spoken to by the Herald said evacuating was the right call given the uncertainty – “better to be safe than sorry” – while one man believed the warnings were unwarranted and risked demotivating people to take action when it really mattered.

So, who makes these calls on weather and emergency responses, and how do they do it?

Inside MetService is the “severe weather bench” – a team of 14 meteorologists whose judgments carry national consequences.

They are some of the most senior operational forecasters in the organisation, responsible for deciding when a system moves from watch to warning, and when conditions warrant the highest level of alert – red.

Those decisions are never made lightly and never made alone, MetService’s Severe Weather Services manager William Nepe explained.

On a typical day, three of the severe weather forecasters lead national decision‑making.

One is focused on small intense systems – think thunderstorms and tornadoes.

Another is on big-scale systems like cyclones and fronts–- systems that last for days and over a large area.

A third acts in an expert support role.

“Forecasters who become severe weather forecasters would have at least 10 years’ experience generally, so you’ve got a lot of experience forecasting the weather in New Zealand.

“Some of my team have been on the job as a meteorologist, not necessarily severe weather, for 40 years ... and have seen a lot of events.”

But, as Cyclone Vaianu spun southward, the severe forecast team numbers were boosted to five, including Nepe himself.

Nepe joined MetService in 2002, became a severe weather forecaster in 2016, and has worked through headline events, including the Auckland Anniversary floods and Cyclone Gabrielle.

The forecasters also coordinate with the wider forecast room which has about 15 meteorologists completing various tasks.

“We try and get as many people into the decision as possible so we don’t miss anything.”

Forecasting severe weather relies a lot on computer modelling but human assessment is critical, Nepe said.

Meteorologists are constantly comparing real‑time observations of satellite imagery, radar, barometers, anemometers and ocean buoys. Then they compare different models and how they behave over time.

The analysis is then weighed against pre‑defined warning thresholds.

“If we see evidence in the modelling that we’re going to exceed those thresholds, we’ll issue either watches or warnings.

“And if those values start to far exceed those thresholds and look like numbers that are unusual or potentially extreme, then we might be considering red warnings.”

During extreme weather events, MetService liaises with councils, Civil Defence, and other agencies to get information – not about the weather but what vulnerabilities or risks exist in a region.

This is key information such as past rainfall, whether the ground is saturated from previous storms, damaged infrastructure or major public events.

That information becomes especially important when considering red warnings, which are impact‑based, rather than simply based on incoming weather.

“Red warnings are about impact.

“It’s not just, ‘Okay, our wind threshold is 110km/h and we’re expecting 120′.”

“It’s about do we expect trees to get blown over and fences to get picked up and roofs blown off.”

One key reason for issuing warnings for Vaianu was it being school holidays and a weekend. More people than usual were going to be at the beach and in the possible firing line.

Around lunchtime on Wednesday last week, with Vaianu bearing south, MetService issued a yellow strong wind watch for the entire North Island – unusual but not unprecedented, Nepe said.

“But given what we were seeing at the time and the potential track, we felt it was necessary to provide that warning.”

At that early stage, MetService knew wind rather than rain would be the main issue with the fast‑moving storm.

The watch was intended to signal risk, not certainty, prompting people to adjust their plans while the system was still days away.

On the Friday, MetService issued more than 20 orange severe weather warnings for wind and rain, with one red alert – signalling risk to life and widespread damage – for Great Barrier Island and the Coromandel.

Finally, on Saturday, the orange wind warning for Bay of Plenty was upgraded to red.

“This was with the holidays in mind, and people being out and exposed to these potential conditions,” Nepe said.

MetService began liaising with councils, districts and specific contacts – the who’s who to contact during extreme events.

“Over and above that we do have requests to attend multi-agency briefings ... you’ve got mayors and all the various stakeholders that are trying to plan and prepare for the upcoming severe weather.

“We’ll provide the weather briefing and we’ll answer any questions that they might have. Then they’ll use that information to make their decisions.”

With the cyclone still pushing south and a touch further east, media coverage ramped up and states of local emergency were announced.

On Sunday, mandatory evacuations were ordered for low-lying areas in the Whakatāne District.

“This is not the storm we were preparing for yesterday – it is worse," acting Whakatāne district mayor Julie Jukes said in a statement late Sunday morning.

“The track has shifted and we are now directly in the firing line. If you are in Ōhope, coastal Thornton, or anywhere you feel unsafe, get out now.”

Vaianu did cause damage. Thousands suffered power outages, flooding hit the Coromandel, numerous roads were blocked and plenty of trees fell in the 100km/h-plus winds.

But, overall there was a sense that the country dodged a bullet, especially with the storms slight push east diminishing the impact on population centres like Auckland.

It was also Vaianu’s fast movement that ultimately limited rainfall totals and the duration of peak winds in many areas, Nepe said.

As the clean-up got underway and it became apparent the overall damage was minimal, criticism of seemingly unnecessary weather warnings and over-hype grew.

Critics argued that both weather warnings and emergency actions were unnecessary and had been amplified by exaggerated media coverage.

In commentary on Ryan Bridge Today the storm was labelled a “fizzer” and risked people not taking warnings seriously.

“In Auckland where I live most shops were closed and they didn’t need to be.”

The debate was laid out when Emergency Management and Recovery Minister Mark Mitchell appeared on the Mike Hosking Breakfast show on Newstalk ZB.

Hosking: “You would side with a MetService that tells me, one – we’re not sure yet, but this is what we think is going to happen. And by the way, change your holiday plans, tie down a trampoline and run for your life. They’re allowed to say that, are they?”

Mitchell: “Well, I just think that, yes, they are allowed to say that because the counter to that is that we start losing lives.

“And in this year, I’ve had two weather events. We’ve lost people – people have died. So we’ve got to protect lives, we’ve got to protect property.

“And by the way, if you do not get these responses right, they have a direct impact on the recovery and it costs us hundreds of millions of dollars as a country, and look, we cannot afford it.”

For Mitchell, the larger risk was a population being inattentive.

“We just can’t live in this world anymore with this complacency. And it doesn’t mean that we need to be alarmist, but we’ve got to be prepared – and we’ve got to make sure that we take this stuff seriously.”

MetService is acutely aware of concerns about over-warning and public fatigue – particularly when impacts don’t match worst-case forecasts, Nepe said.

“We do take these decisions seriously ... we’re trying to provide warnings with the best information.

“We’ve got to be removed from that and just think about the meteorology, our thresholds and the potential impacts.

“If it doesn’t work out I’ll defend our forecasts – I’ll defend our decisions.”

When the Herald talked with Nepe on Tuesday, he was drained. He said forecasting big weather events and issuing red warnings was hard work and time-consuming.

Plus it had been a busy year – Vainau was MetService’s fourth red warning event during 2026 and going by the impacts, the previous ones appeared to have been warranted.

So far in 2026, at least 11 people have died in weather‑related incidents across New Zealand, the majority during January’s upper North Island storms, which involved catastrophic rain and landslides, followed by one flood‑related death in Waikato in February.

Those deaths occurred across events that triggered multiple MetService red heavy rain warnings in January and February.

Besides the deaths, there had been widespread damage – houses destroyed by flooding and slips, bridges and roads washed out and extended power outages.

After each event, MetService reviews forecasting performance and decision-making, looking not only at what happened, but also whether processes could be improved.

“We do look for any learnings and that’s not just the weather forecasting itself but also processes, procedures, anything that could help streamline or do things differently,” Nepe said.

“And absolutely those have led to us doing things differently.

“But wind is a bit different to rain,” he said.

The impact can be sudden and extreme if people are out and about and exposed – a reason to issue warnings.

“You only need one gust for a tree to fall on a car and someone dies.

“I am feeling quite glad people weren’t out – we don’t know how many lives we may have saved.”

Mike Scott is an award-winning visual journalist with more than two decades of experience telling stories across multiple media platforms.

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