"That's going to come with some warmer temperatures – especially compared to what we've seen so far this season."
One widespread period of warmth, forecast to begin around Labour Weekend, could see the mercury edge past 25C for the first time this spring.
"It's been a little sluggish in this regard, just because we've had so many easterly onshore winds in areas like Canterbury, Otago and Hawke's Bay – and these places will be tapping into these early, warm temperatures, too," Noll said.
"So, this period could prove a bit of a teaser for the temperatures we'll get over summer."
What's behind the change?
The obvious answer might be summer approaching, but there's much more going on in the background.
Noll said the past few months have seen major climate influencers, in particular, jostling for control of our local weather patterns.
One has been the effect of a far-off ocean-atmosphere driver called the Indian Ocean Dipole – and the negative phase it's long been locked in has made for an especially soggy spring across the Tasman.
Another is what's called the Southern Annular Mode – indicating storminess deep below New Zealand – that's been fluctuating between negative (think colder, unsettled weather here) and positive.
The third, which Kiwis have been hearing increasingly about, is La Nina: another ocean-driven system that had its fingerprints on what was our warmest, wettest winter on record, and has also flavoured our past two summers.
"As we head into the tail-end of the month, La Nina really nudges those other hands away from the steering wheel, which means we get less of the variability we've had," Noll said.
"It also means we'll probably see warmer temperatures on the whole."
That's in line with the above-average temperatures Niwa has already picked for New Zealand for the rest of 2022 in its three-month outlook – especially across the North Island and west and north of the South Island.
Is drought a risk?
It's still too early to suggest that with any certainty: but last summer's La Nina happened to culminate in medium-scale events in Otago, Southland and Rakiura/Stewart Island.
Over the past two months of the year, strong highs - especially in and around the South Island – were expected to deflect incoming lows and keep them right up toward the top of the country, leading to increased odds for dryness elsewhere.
While there was an elevated risk of dryness in the southwest of the North Island and in the west of the South Island, the odds were below or near normal in the west of the north, and the north and east of the South Island.
"There'll likely be more regions experiencing dryness than not – but our focal points will be places like Nelson, Tasman, West Coast, Otago, Southland, and perhaps even parts of Canterbury too. Wellington, the Kapiti Coast, Manawatu-Whanganui, and Taranaki are also regions to watch."
Prolonged periods with little rain could easily churn through the soil moisture that had been built up through our abnormally wet winter.
Is it going to be all blue skies?
Definitely not: depending on where you live, the last two La Nina summers may have been unusually warmer, cooler, wetter, drier, windier, or calmer, such is the geographic spread it comes with.
Around the end of this month and in early November – when a globe-circling pulse of rainfall called the Madden Julian Oscillation travelled closest to New Zealand – there was a higher chance of a sub-tropical-flavoured deluge.
As well, Niwa's latest outlook for the tropical cyclone season warned of an elevated risk earlier, or between November and January.
"So, we'll certainly be keeping one eye on what's going on in the tropics."
And how about marine heatwaves?
Noll has warned that marine heatwave conditions this summer could possibly grow as severe as the two largest events we've ever recorded here – with big implications for what happens on land.
While many parts of our coast have been experiencing persistent marine heatwave conditions – and sea temperatures were forecast to jump up again over coming weeks – Noll didn't expect us to be feeling the effects on land until mid to late summer.
"These do take a while to really get established and cause a positive feedback loop – and right now, we're still only looking at the formative stages."
