The Front Page: Summer ruined as rain records broken – how much more can our cities handle?

Record rainfall has wreaked havoc around the country.

Today is the last day of summer, but North Islanders could be forgiven for not noticing. Relentless downpours have rendered the last three months the wettest in living memory.

Niwa meteorologist Ben Noll tells The Front Page podcast that the extent of the rain records broken actually goes far beyond the memory of anyone living today.

“The rainfall this summer is likely to go into the record books as being a record wet summer for many locations – and our record books, in some cases, go back to the 1800s,” says Noll.

“When you’re breaking records over 100 years old, that’s pretty important. And the magnitude by which we are breaking some of these records makes it seem like it will be very difficult to top this summer from a rainfall perspective.”

New Zealand has always had a relatively wet climate, but the quantity isn’t the only factor that made the summer of storms particularly destructive.

“What we’ve seen is not just extremely high rainfall totals, but also extraordinary rainfall intensity, which has come [from] thunderstorms or extremely heavy showers that have sat over one location.

“In the instance of Mangawhai, north of Auckland, on Friday, there was an extraordinary amount of rainfall in the course of a 24-hour period: nearly 400 millimetres recorded by one of the Northland regional councils in 24 hours. More than 200mm of that came in about three hours.”

Noll says this rainfall equated to around seven times the rainfall that you would expect to see for a whole month in February.

“That’s going to be a challenge for any piece of infrastructure, whether it’s a road or your home. That level of rain will have an impact no matter how well-built or well-situated you are.”

No matter where you look across the North Island, there are similar examples of records simply being smashed over the last three months.

“We’ve had 200 to 400 per cent of normal rainfall, so two to four summers’ worth of rain for many regions. And that puts us up to around 400 to 800mm of rain this summer. As of last week, before the big rain on Friday, Auckland had received 56 per cent of its normal annual rainfall in just the first two months of 2023. That puts some perspective on just how extreme the summer rainfall has been.”

The concerning thing is that there could be more to come, with meteorologists currently keeping an eye on an area of low pressure forming in the Pacific.

“Another tropical cyclone is forecast to form and it’s expected to hammer Vanuatu over the coming days with wind, sea and wave-related impacts,” Noll says.

“As we look toward the first week of March, that cyclone, which is expected to become a Category 3 cyclone, will track southward. For New Zealand, around that time, there may be an area of high pressure that emerges from the Southern Ocean.”

Noll says that this high pressure may function as a “stop sign” that prevents this cyclone from moving too close to our shores – but this forecast could still evolve.

“That’s how things are looking right now, but given it’s still five to seven days away, the cyclone hasn’t quite formed yet. There is still some uncertainty and we’re going to need to keep a really close eye on it.”

This ultimately means it will be a nervous few days for those that have already been rocked by the summer of storms.

So, how much more rain can our North Island cities take? What can we learn about cyclone preparedness from places like Florida and Louisiana? And do we need to have a better plan in place for cyclone season?

Listen to the full episode of The Front Page podcast to hear Noll answer these questions and more.