Weather: After a chilly May, what’s in store for winter?

After a noticeably chilly May, Niwa has picked milder temperatures for winter — albeit with another potential deluge in mid-June.

The agency’s just-issued seasonal climate outlook for the next three months has given equal chances for near or above-average temperatures over New Zealand.

The season was expected to kick off with a spell of warmer temperatures, before a return to more typical conditions over the second half of June.

“Cold snaps, while expected occasionally through the season, will likely be brief,” Niwa reported.

The season was also likely to bring more of the dry weather that’s left swaths of the country’s east dry throughout summer and autumn – with rainfall events likely to occur “irregularly”.

However, Niwa was monitoring the chance of a heavy rainfall event in the North Island and northern South Island during the second week of June.

Overall, the outlook picked near-to-above-normal rainfall in the west of the South Island — but near or below-normal levels everywhere else.

Because air pressure was likely to be higher near the North Island, but lower south of the country, Niwa also expected to see more westerly winds blowing through New Zealand.

But southerly winds weren’t predicted to be as frequent as they were in autumn, “which will have an influence on temperature patterns”.

That change came with the demise of El Nino — the climate driver that’s been shaping our weather since spring last year.

While New Zealand was now under an “ENSO-neutral” regime — meaning no major climate driver was at the steering wheel, enabling more variability — La Nina was likely to return during spring.

However, that didn’t mean the country was in for a repeat of the disastrous La Nina summer of 2023 that was the result of ocean warmth built up by three back-to-back La Nina events and global climate change, among other factors.

Meanwhile, MetService is forecasting a calm long weekend over most of the North Island —but unseasonably warm temperatures, gales, and heavy rain herald the first day of meteorological winter for the South Island.

“The upper North Island can expect calm, settled weather for the long weekend and the beginning of meteorological winter,” MetService meteorologist Clare O’Connor said.

“In the South Island, however, a developing northwesterly flow is going to bring heavy rain to Fiordland and the ranges of Westland from late Friday, and strong winds to the east of the South Island.”

Hawke’s Bay was probably the place to be on the weekend, with maximum temperatures forecast of 23C on Saturday, and Monday offering the best weather for the whole country.

Jamie Morton is a specialist in science and environmental reporting. He joined the Herald in 2011 and writes about everything from conservation and climate change to natural hazards and new technology.