One of the wettest and warmest July months ever recorded in Northland has a climate scientist warning the region to get ready for “a new normal” of winter downpours coupled with summer droughts.

Newly released
data from the National Institute of Water and Atmospheric Research (NIWA) shows it was overall New Zealand’s wettest and fourth-warmest July on record, with five significant weather events between July 11 and 31 giving the nation a good soaking.

That will come as no surprise to Northland farmers, firefighters and road workers, who had to deal with sodden pastures, flooded highways, downed trees and roads wiped out by slips.

With a whopping 572mm of rain, Kerikeri was the second-wettest place in the country, beaten only by Aoraki-Mt Cook’s 725mm.

That’s almost three times Kerikeri’s July average and the second-wettest since records began in 1935.

Kaitaia’s 301mm, almost double the long-term average, was the town’s third-highest July rainfall.

The July 25 deluge in particular flooded SH10 north of Kaeo and SH1 at Rangiahua and left about 2000 Bay of Islands homes without power, while earlier storms destroyed sections of West Coast Rd – cutting Panguru off from the outside world – and Waiotemarama Gorge Rd near Ōmapere. Many schools were forced to close as roads became impassable.

SH1 at the bottom of Moerewa’s Turntable Hill, however, stayed open thanks to a flood prevention project completed just last year.

Not only was July wet, it was also unusually warm.

Despite a few cold snaps, much of the region recorded record or near-record temperatures.

The mean air temperature in Kaitaia was 14.0C, a full 2C higher than normal and the highest since records began in 1948.

Kerikeri (13.3C) and Dargaville (13.2C) recorded their second-highest mean July temperatures while Whangārei’s 13.4C was its third-highest.

On July 9, Whangārei experienced an almost summery maximum temperature of 20.4C and Kerikeri 20.1C. Those were the third- and fourth-highest, respectively, on record.

NIWA climate scientist Nava Fedaeff said Northland was already experiencing climate change.

“It’s not necessarily something off in the future. We’re already living in it,” she said.

Overall New Zealand recorded its warmest-ever winter in 2020, a record that was promptly broken in 2021.

Fedaeff expected the warming trend would continue, though that didn’t mean Northlanders would never again experience a cold winter.

Predicting future rainfall was more complicated. Higher temperatures meant the air was able to hold more moisture, which meant more rain.

However, in Northland’s case, even if total rainfall remained roughly the same, it was likely to be distributed unevenly throughout the year with more flooding in winter and long dry spells in summer.

That “new normal” would make planning and water management difficult for the region’s vital primary sector.

This year was also likely to bring the third La Nina weather pattern in a row, with long periods of dry, settled weather this coming summer, only broken up by occasional tropical storms – though the rain they brought could bypass Northland, as happened last summer.

It wasn’t all bad news however, with July’s rain helping recharge groundwater depleted by a series of summer droughts.

“There are also new opportunities for Northland because the climate could become more favourable to new industries and crops, as long as people take climate change into account when they’re making long-term decisions,” Fedaeff said.

A number of water security projects, including a series of Provincial Growth Fund-funded dams near Kaikohe and on the Pouto Peninsula to capture winter rain for use in summer, are already underway.

July’s biggest weather events were the so-called “atmospheric river” of moisture on July 11-12 and a sub-tropical low on July 25-26. Both brought heavy rain and strong winds, though Northland dodged the worst of the wind.

The only town which came close to setting a local wind record was Kaikohe with an 82km/h gust on July 12, its fourth-strongest on record. That was, however, a breeze compared to the 163km/h recorded at Fiordland’s Puysegur Pt.

Northland farmers weathering the deluge

Northland farmers say July’s record rainfall was tough on people and stock – but also that they’re a resilient bunch who can adapt to whatever the climate throws at them.

Ōkaihau dairy farmer Terence Brocx said his farm had copped even more rain than the 572mm recorded at Kerikeri.

“We’ve been able to manage it quite well because we’ve had no flooding. For us it’s been about trying to protect our pasture so a lot of work has gone into that. It’s been pretty hard on people and pretty hard on animals, but this week of finer weather has certainly lifted spirits.”

Brocx said he was fortunate in that he had a feed pad so he could stand cows off and limit pasture damage.

The higher than normal temperatures had boosted pasture growth but the heavy rain meant most of it was pushed into the soil.

If NIWA’s predictions of ongoing dry summers and wet winters proved correct, that would add significant extra cost and challenges.

However, farmers already had systems in place to deal with summer droughts.

“Weather’s cyclic and farmers are pretty resilient. They’ll adapt.”

Former Federated Farmers Northland dairy chairman Matt Long said temperatures at his farm inland from Tūtūkākā had been good for pasture growth but the wet conditions made it hard to avoid pasture damage.

“The weather really makes things difficult for everyone. Also, it’s been so wet everyone runs through feed really quickly.”

A shift towards wetter winters and drier summers would be bad for dairy farmers, but he’d been experiencing seasons like that for the past decade and believed it was cyclical rather than a long-term trend.