Vaianu a fizzer? Wellington a flub? Can’t the forecasters get it right?

Tuesday, 21 April 2026

Reid Basher is a retired senior adviser in the UN International Strategy for Disaster Reduction.

OPINION: Last week, Cyclone Vaianu passed by, causing less damage than expected. But now, a week later, it’s the opposite: heavy rain and flash flooding in the Wellington region is causing more damage than expected.

Brace for the blowback: some say Vaianu’s warnings were over-hyped and misled the public. Others ask why there was so little warning of Wellington’s flash floods.

Let’s start with Cyclone Vaianu. After days of shock-horror predictions and emergency advice had been promoted in the media, the cyclone seemed to weaken. Some commentators said people felt misled into preparedness actions that in hindsight seemed silly and unjustified. Wairoa’s Mayor, Craig Little, was even reported as saying we're becoming woke as a country when it comes to declaring states of emergency.

Yet Vaianu had certainly looked big and scary in the satellite images, and was moving straight towards New Zealand. The media briefing on 8 April by John Price, head of the National Emergency Management Agency (NEMA), referred to heavy rain and extremely high winds, and provided normal, sensible preparedness advice.

Read more:

• Night-time escapes from floodwaters: Ruapehu mayor says better warnings needed

• Why the forecasts didn’t forecast this: Two floods, man missing, state of emergency

• Wild weather claims triple as storms become near-weekly threat

In the following days, severe weather warnings were issued and updated by MetService and many regions declared regional or local states of emergency. Not Wairoa though.

In the event, some North Island areas were badly affected by very high winds and high rainfall that caused power outages, flooding and road closures, but the cyclone’s track luckily trended eastward as it approached, sparing us from the most extreme conditions.

Strangely, some people felt short-changed rather than happy by this, and argued that the emergency authorities shouldn’t go the whole hog on scary warnings until they’re absolutely certain of the storm’s final path.

That’s a superficially attractive but fatally wrong strategy. It would be like putting your foot on the brakes only when you are sure the other car really is going to hit you.

When things are threatening, the right approach is to pay attention and progressively prepare as firmer information becomes available on what’s likely to happen. That’s true for cyclones as well as for deviant drivers.

The fact is a cyclone’s path and strength are not fixed a week ahead. The track can meander, the winds may become stronger or weaker, and the rainfall may become heavier or lighter.

Also, remember we’re still suffering a bad hangover from the early 2023 North Island floods and Cyclone Gabrielle disaster, when unprecedented rainfalls in Auckland on January 27, 2023 shocked the meteorologists, and flooding was far greater than expected. People were unprepared, and tragically some died as a result.

Now pivot to Wellington. As I write, a state of emergency has been declared. Torrential rainfalls, flooding and landslides overnight on Sunday in the Wellington’s central and eastern suburbs added to the earlier downpours and floods in Plimmerton and Upper Hutt.

The MetService heavy rain warnings for the region are hard to fault. They included the risk of thunderstorms and the possibility of worsening conditions that would be a threat to life, from dangerous river conditions, significant flooding and slips.

It’s the convective thunderstorms that are the problem. They can drop as much as 100 mm of rain in an hour, but are simply not very predictable, even a few hours ahead. If one of these coincides with your suburban valley, you could be in for flash floods and landslides, while for the neighbouring suburbs it may be “only” heavy rain.

The fickle, unpredictable nature of convective storm location and intensity means that everyone is potentially at risk, but only some places will get the full works.

In the case of Cyclone Vaianu, in addition to not appreciating the vagaries of cyclone behaviour, many people wrongly interpreted the growing media hype as a guarantee of impending doom.

The media plays a vital role in communicating warnings and emergency preparedness to the public. But we all know that the media amplify bad news and negative vibes. The fear, once established, is hard to dispel. One Facebook user was onto the problem, saying that Cyclone Vaianu was being used as clickbait and people should “prepare appropriately and not get sucked into their fear porn”.

For sure, no-one likes a false alarm, but as I said in a Post article this time last year, it’s better to have an overshoot and be over-prepared, than to have an undershoot and suffer.

Were the forecasts for the Wellington storms an undershoot? Not if you read them carefully. But maybe we need better story-telling to help us visualise what might potentially happen.

Likewise, I think it’s a fair concern that during Cyclone Vaianu many people, like Wairoa’s Mayor Little, felt pressured toward actions that seemed performative rather than sensible in terms of what they were personally seeing and hearing as the cyclone closed in.

We know that early warning systems are well-proven as cost-effective tools for saving lives and money – so long as the warnings reach those at risk, the affected people understand the warnings, and they do the right things in response.

New Zealand does pretty well with its warning systems, but it looks like there’s still room for improvement, including through more proactive management of key messages, especially on social media and radio. That’s something for MetService, Nema and the media to keep working on in future.

This article is partly based on an earlier version published at reidbasher.substack.com.