'Unsettled' Autumn: Bay of Plenty to see mixed bag of weather over next three months

Autumn rainfall would be good news for parts of the Bay of Plenty. Photo / File

An "unsettled" autumn is set to hit the Bay with a mixed bag of summer-like temperatures, cold snaps and rainfall.

However, the downpours will likely not be enough to restore the region's soil moisture or significantly bolster the city's river flows.

A meteorologist said climate readings showed that dry summers followed by "binge rainfall" were becoming the norm - spelling trouble for many of the region's farmers scrambling to adapt.

Temperatures were likely to be average or above average over the next three months while soil moisture was expected to be below average, according to the Niwa seasonal climate outlook.

Bay of Plenty Regional Council water shortage event manager Steve Pickles. Photo / Supplied

River flows were forecast to be down but rainfall was expected to sit at near average.

Autumn rainfall would be good news for parts of the Bay of Plenty including Tauranga where water restrictions over part of summer banned sprinklers and hard-surface hosing as demand for water spiked.

Meanwhile, the Bay of Plenty Regional Council put a new water management system in place over summer as water levels in streams across the region rapidly dropped.

In Rotorua the Ngongotaha stream fell to the lowest water levels in 50 years.

In February, Tauranga had only six days of rainfall with the most being 43.4mm on the 15th and a monthly total of 68.8mm. The highest temperature of the month was 27C on the 12th.

In the same month, Rotorua had 10 days of rainfall with the largest amount falling on February 16 at 26mm and a monthly total of 70mm. The highest temperature was 27.5C on the 20th.

Niwa principal scientist Chris Brandolino said the Bay of Plenty could expect more "variable conditions" as autumn hits and the region experiences a "blend of flows".

He said the region would see "warmer temperatures" but also could expect the odd "cold snap" and "unsettled weather" similar to this week's conditions.

Consecutive dry days that had been consistent throughout the summer would be less likely to persist but autumn would "begin on a dry note", he said.

Although normal rainfall was expected, he said this would not necessarily fulfil the soil moisture needs due to the deficit it was already facing.

Dry summers followed by "binge rainfall" were becoming the norm and this would only become more extreme as climate change became more prevalent over the decades, he said.

"We can expect the same amount as previous years but the distribution will change. It will come in bunches.

"This is an example of our expectations of the future, climate change has a footprint."

MetService's outlook for March showed that the first half of the month was looking to have a "very autumnal feel to it" and would be "cool and unsettled" while the second half would have a "more summer-esqe feel" as high pressure took over again.

In April and May, as La Niña tapered off low-pressure systems around New Zealand were looking to become more frequent.

Federated Farmers Bay of Plenty president Darryl Jensen said rain in the first week of March had been "just brilliant" and well-needed for many farmers.

He said repeated dry summers meant soil moisture was in deficit and good autumn and winter rains were needed to "recharge" growth.

Many farmers, especially in the Paengaroa and Te Puke areas, were seeking out new water sources as wells and other water sources had been "compromised or dried up", he said.

Federated Farmers Bay of Plenty provincial president Darryl Jensen. Photo / File

Jensen said increased extreme weather events meant that many farmers were having to look at ways of changing their farming systems to adapt to the possibility of annual drought-like summers followed by hard downpours.

Federated Farmers and other industry leaders were tossing around ideas on how to stockpile feed and create solutions for the climate problem to ensure farming stayed sustainable and affordable, he said.

Farming "certainly will change" over the next few decades due to weather, just like it had changed over the past 50 years, he said.

Bay of Plenty Regional Council water shortage event manager Steve Pickles said the recent rainfall across the Bay of Plenty had reduced the rate at which water flows were dropping, however, stream levels in the Focus Zone remained low.

Although there were no immediate water restrictions planned at this stage, forecast dry conditions might still cause stream levels to drop further, possibly resulting future restrictions, he said.

Council principal adviser of policy and planning Nicola Green said they were working towards making changes to their Regional Natural Resources Plan by July 2024 which would introduce clear minimum flows for rivers and new policy directing water take.