A lone fisherman braves the heat of Hawke’s Bay at Napier’s Perfume Point. Niwa predicts weather that looks more like summer – especially in the northern and eastern regions – through to autumn. Photo / Paul Taylor
Summer-like conditions are expected to persist well past the end of the season in already dry parts of New Zealand – with some bags now roasting in severe drought.
Niwa latest views over the next three months there is a longer, hotter dry season across the country – and the potential to reduce rainfall in places north and east that feel mostly hot.
That pattern is driven by the bizarre La Niña climate system, which traditionally brings many northeastern storms to normally dry areas.
Which is called “hot spot” – or places with very dry to very dry than usual soil conditions – have now developed over large parts of Northland, parts of Auckland, northern Waikato, and parts of the East Cape.
Meteorologists also keep an eye on the hotspots in eastern Wairarapa which are scattered in the eastern Tararua District and the Hawke’s Bay coast.
The worst conditions can be seen in the upper Far North, which has officially achieved meteorological drought status.
Although some rain is expected to fall later this week, it is likely that the hotspot – especially those in the east – will only continue to expand.
Fire hazard currently very high at the tip of the North Island, and around Dargaville, Whangarei and parts of Eastland, Porangahau, Tararua and Wairarapa.
On the South Island, there is also a high risk around McKenzie Village, and most of the coast of Marlborough and central and northern Otago.
Over the next three months, Niwa forecast above-average temperatures in the north – and close to above-average temperatures elsewhere.
“We’re going to have some warm conditions that will probably last until March – and maybe April too,” said forecaster Niwa Ben Noll.
“It won’t be summer without stopping during those months – but chances are we’ll have a spell that’s like summer, overall.
“What we can see are high pressure mountains, curving over New Zealand for maybe a week or so, before being disturbed by features like we expect from the Tasman Sea. [this week].
“But the northern and eastern parts of the North Island, which are currently the driest areas relatively normal, have the lowest chance of feeling the full effect of the feature.”
Noll noted that this dry weather followed an equally hot summer last year, resulting in Auckland’s worst drought in 25 years.
“Several locations in Auckland also have the record for driest years in 2020. Piling this on top is a tough combination.”
Auckland dam level is still recovering well, and as of the week, is running at 61 percent capacity – and more than 20 percent below the historical average for this time of year.
With Auckland needing to limit its water use to 511 million liters per day, restrictions installed throughout the city which prohibits the use of hoses not equipped with a trigger nozzle.
However, the regulation is not expected to be tightened.
“At this stage, we are confident that our new water source, coupled with Auckland’s excellent water savings, will help us get through the summer and fall without the need for more severe water restrictions,” said a Watercare spokesman.
Noll said La Nina influencing the behind-the-scenes image will likely prove to stand out in the record books, given its dramatic “non-traditional” behavior.
Most of the La Nina-flavored summers usually come with widespread warmth, but also storms from the northeast, rains in the north and east, drought in the south and southwest – far different from what New Zealand saw this summer.
That can largely be explained by two factors.
One of these is the fact that the coldest ocean temperatures in the Pacific below La Nina are found farther west than usual, meaning much of its traditional tropical activity is centered elsewhere.
The other is warmer than average temperatures in the Indian Ocean, which, combined with the unusual La Nina, result in a different climatic setting for New Zealand.
Current models suggest La Nina is likely to stick around for the next few months, before largely disappearing by winter.
Meanwhile, one of La Nina’s classic effects – warmer ocean temperatures – is at least in part, with pockets of sea around the north of the North Island reaching “ocean heat wave” conditions last month.
During January, coastal waters around New Zealand ranged from 0.3C to 0.7C above average – but it remains to be seen how long this trend will continue.
Noll says the picture is a far cry from the 2017-18 and 2018-19 summers, where repeated ocean heat waves pushed ocean temperatures several degrees above average.
“To make that happen, you need currents that extend from north to northwest – and we have too much variability to allow for that.”
While there is no immediate threat from a tropical cyclone affecting New Zealand, Noll said there is potential for activity at the end of the month.
Every year, on average one of these systems sweeps within 550 km of the country, bringing destructive winds and heavy rainfall.
So far, the cyclone seasons have gone hand in hand predicted range of eight to 10 systems in the southwest Pacific, with four recorded so far.
“Of course, the season runs through April, so we are keeping an eye on if anything will actually land here in New Zealand.”
Last month marked four years since New Zealand last experienced a month with below-average temperatures – a trend driven by climate change.
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