New Zealand’s summer will start with “more widespread dry conditions”,”above average temperatures” and the potential for “short and intense rain events”, according to a NIWA seasonal climate outlook released today.
The outlook, which covers November 2024 to January 2025, indicates the likelihood of climate conditions being at, above, or below average for the season relative to the 1991-2020 average.
NIWA said there was a “little over 50% chance” that La Niña officially develops by the end of the year.
“However, this event is likely to be weak and short-lived and might stay below traditional La Niña thresholds.”
La Niña is a climate pattern that describes the cooling of surface-ocean waters along the tropical west coast of South America.
It is considered the counterpart to El Niño, which is characterised by unusually warm ocean temperatures in the equatorial region of the Pacific Ocean.
NIWA said there were indications for “more widespread dry conditions” than a typical La Niña event across much of the country towards the beginning of the three-month period.
“Rainfall is most likely to be near normal in the east of the North Island and about equally likely to be near normal or below normal for all remaining regions of the country.”
An increased chance of anticyclonic conditions over and to the southeast of New Zealand may lead to dry spells developing in the west of both islands, NIWA said.
“La Niña-like conditions could on the other hand bring short and intense rain events for the north of the North Island and the eastern parts of both islands.”
The research institute also said air temperatures were “very likely” to be above average and that a prevalence of northeasterly winds could lead to more days above 25C than normal.
Marine heatwave conditions were currently occurring near the southeast of the North Island, the east of the South Island and along the west coast of the North Island to a lesser extent — and NIWA suggested these conditions could intensify in the coming months.
Hope for hard-hit Southland rural communities
There was hope on the horizon for rural communities in Southland who have experienced the wettest spring on record.
Temperatures in the region are very likely to be above average and rainfall totals are likely to below or near normal. Extended dry spells are predicted and soil moisture and river flows are likely to be near or below normal.
Environment Southland compliance manager Donna Ferguson said the recent wet weather has had a “huge impact” on communities across the region.
“We’ve been heartened to see some good examples of pond and irrigation management under the circumstances.
“We feel for consent holders, farm managers and their teams and encourage anyone in need of support to reach out.”
