Niwa picking hotter-than-average temperatures for early summer

Niwa is forecasting above-average temperatures for the next three months, as another La Niña system keeps a "firm grip" on the steering wheel of our regional climate. Photo / Brett Phibbs

Niwa is forecasting above-average temperatures for the next three months, as another La Niña system keeps a "firm grip" on the steering wheel of our regional climate.

Its latest long-term outlook, covering November to January, predicted widespread warmth, with a "very likely" probability of hotter temperatures in the north and west of the country.

That would come with periodic humidity and a shift from relatively cooler conditions that Kiwis felt earlier this month.

There was also potential for a dry spell to develop during the second week of November.

"Such periods will occur occasionally through the season, increasing the risk for lower-than-normal soil moisture," Niwa reported.

"These dry periods may be occasionally interspersed with tropical downpours, especially in the north."

Next week, particularly, was expected to bring a period of strong northwesterly winds and heavy rain in the western South Island.

"This marks a period of intra-seasonal variability when weather patterns briefly diverge from the typical La Niña regime; this is expected to occur at times over the next three months."

Over the wider three-month period, rainfall levels were equally likely to be near normal or above normal in the east of the North Island, most likely to be near normal in the north of the North Island, and equally likely to be near normal or below normal everywhere else.

Higher-than-normal air pressure over and to the south of the South Island – but lower-than-normal pressure north of the country – would likely lead to more easterly flows, and fewer westerly winds.

"La Niña very much has a firm grip on the steering wheel – and that is expected to continue through the next three months," Niwa forecaster Ben Noll said.

He expected to see some similarities with last summer – our fifth hottest on record – particularly with the potential for extended periods of heat throughout the season.

"The signs right now are that cooler-than-average periods are going to become fewer and farther between – and even this period we're in now, between late October and early November, is going to be awfully warm in some regions."

Adding to the increasing warmth would rising sea surface temperatures.

While these ranged from 0.3C to 1C above average over October – and cooled noticeably in many areas off our coasts – they were predicted to escalate next month.

Niwa's latest forecasts suggests sea surface temperatures stretching between Tasmania and the Chatham Islands could be averaging 1.1C above normal in January – with many coastal spots likely to see particularly high values.

Compared with what the models had forecast for the region in the past, those forecast temperatures were at the upper-end of projected anomalies - and enough to have widespread implications for land and sea environments.

The year has already brought record-breaking local marine heatwaves – and a slew of other concerning milestones.

Winter 2022 was our warmest for the third year in a row, while the first half of the year was also the second-hottest ever recorded – trends that will only continue as our planet warms.