Jamie Morton is the NZ Herald's science reporter.

New Zealand's big drought - whole country at risk

Serious fire danger despite rain and Auckland's dams well down on norm.
Rain volumes at the weekend weren't large enough to bring relief to struggling farms. Photo / NZME.
Rain volumes at the weekend weren't large enough to bring relief to struggling farms. Photo / NZME.

Rain forecast for this week is unlikely to offset a soil-parching big dry that has put much of the country at serious fire risk and begun to hurt farmers in hot-spot areas.

Yesterday, farmers and fire officials welcomed long-awaited rain throughout most of New Zealand - but doubted it would bring any meaningful relief to those places that had received little of their normal levels this season.

What has been one of driest summers yet has led Federated Farmers to predict official drought declarations are "on the cards".

The National Institute of Water Atmosphere (Niwa) has described nearly all of the North Island and much of the South Island as a "hot spot" where soil conditions are much drier than normal.

Only sustained rainfall over an extended period would bring the arid areas back to normal.

In Auckland, the city's water storage level yesterday was at 71 per cent - 10 per cent less than the average for this time of year - but no restrictions have been introduced.

While rain forecast in coming days for central and western parts of the North Island could prove enough, it would likely fall well short of what is needed in other hot spots.

National Rural Fire Authority executive Gary Lockyer said fire-danger conditions remained severe in parts of the Waikato, the Central North Island, Canterbury and Otago.

After a week that saw 15 vegetation fires - including one that scorched more than 330ha of tussock and forest near Arthurs Pass before nearly 50 firefighters could put it out - the risk of scrub fire was considered extreme across a large swathe of the South Island, as well as pockets of the North Island's east coast.

The weekend rain might have brought some respite to busy fire crews, Mr Lockyer said, "but all in all, there won't be a lot of change".

"We are now heading into February, and the situation is already reasonably serious, because by now we normally would have seen some easing of conditions in some regions.

"Fire danger levels are widespread right across the country, and apart from the West Coast and Southland, there's no one region that's good."

Federated Farmers adverse events spokeswoman Katie Milne also wasn't aware of any volumes at the weekend large enough to bring relief to struggling farms. "You really do need quite a lot and over a nice slow period for it absorb. If you just get a cloud burst, it basically runs off because the ground is like concrete."

Although no droughts have been officially declared anywhere, Federated Farmers is this week opening a hotline for struggling farmers to buy feed.

In hard-hit North Canterbury last week, some farmers were unable to sell excess stock and were forced to take them home, where there was little to feed them.

It could take weeks before the stock could be off-loaded to the works, Ms Milne said, which was a "pretty harrowing" situation for farmers.

"We are at a point now where it could start to get quite ugly. We don't want to have any animal welfare issues, so that's where people have to make good decisions early."

Those finding it especially tough this summer were farmers burdened with extra infrastructure costs after switching to dairy, or those exhausting their irrigation water takes.

Banks were aware of the situation and had been accommodating to financially stretched farmers, Ms Milne said.

The Ministry for Primary Industries, responsible for declaring droughts, had been closely monitoring the dry conditions since December and was in regular contact with rural support trusts and industry groups.

The unusually warmer weather is expected to last through to April, while soil moisture levels were likely to be either near or below normal levels in the North Island and west of the South Island.

Victoria University climate scientist Dr James Renwick said unusually dry summers would become more common under the long-term effects of climate change.

"The likelihood of getting a summer like this should at least double by the end of the century."

Will El Nino make the big dry drier?

For farmers, it's a bogeyman that can bring more weather extremes to an already dry summer. But whether an El Nino pattern will arrive this summer is still unclear - and even if it does, the impact might be only fleeting, climate scientists say.

In New Zealand, the ocean-driven system typically brings cooler, wetter conditions, delivering higher rainfall to regions that are normally wet, and often drought to areas that are usually dry.

Although an El Nino was forecast through much of last year to heat this summer up, it hasn't eventuated - and last week, Niwa put the chances of one developing in the next three months at 60 per cent.

At the last check, sea surface temperatures across the equatorial Pacific Ocean were still between neutral and weak El Nino conditions.

"It really hasn't fired up very dramatically in the atmosphere, so if an El Nino is happening, it will be coming and going," said independent climate scientist Dr Jim Salinger.

The week ahead

Rain is forecast throughout this week - but it's likely to be "showery" rather than sustained, MetService meteorologist Ciaran Doolin says.

A low coming off the Tasman Sea is predicted to bring a moist northerly flow at the start of the week, followed by a series of troughs from the south.

By tomorrow afternoon, showers across the North Island will have become isolated, with rain still in the west and south of the South Island.

While Wednesday will be mainly fine across the North Island, heavy rain is forecast to ease to showers in the west and south of the South Island.

Rain and showers will return in both islands on Thursday and Friday.

- NZ Herald

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