The prospect of an El Niño climate pattern is looking increasingly likely as waters off South America's west coast warm, with some models even tipping conditions for an "extreme" event to occur.
It's a worrying prospect for many farmers in Australia's eastern states who rely heavily on winter rainfall for their grain and pastures to grow.
"It's suddenly turned brown and all of a sudden things in the garden are dying and trees are dying and there is hardly a hint of green," Bunnan cattle farmer Paula Stevenson said.
"There is a slight buffer [from La Niña] and the aquifers have been recharged, but it's just a matter of whether you can access it."
El Niño events have a reputation for bringing warmer, drier weather to Australia.
Nine out of 10 of the driest winter-spring periods on record for eastern Australia occurred during El Niño years, although it does not guarantee it.
It is part of a natural cycle known as the El Niño Southern Oscillation (ENSO) and is one of Australia's key climate drivers.
But Bureau of Meteorology climatologist Greg Browning said there was still a long way to go before an El Niño became certain.
Models agree, but no guarantee
The latest Climate Driver Update from the bureau shows all international models in agreement that an El Niño event will occur by August, with six of seven tipping ocean temperatures to reach the threshold by July.
The Australian model even projects ocean temperatures in the Pacific could warm to a point indicative of an "extreme" El Niño — an event that can severely disrupt global weather patterns.
But Mr Browning said there was still a chance they could all be wrong, with autumn known to be a delicate time of year for ENSO predictions.
"We're in a particular part of the year where the accuracy of the models is a bit lower than what it is at other times of the year," he said.
"And there's still scope for changes in wind regime, or just unforeseen things that could happen to stop an El Niño in its tracks."
This was the case in 2014 when early models were projecting a strong El Niño for the coming winter, but an unusually timed westerly wind burst stopped it in its tracks.
Nevertheless, Mr Browning said ocean conditions were at a stage where it was well on its way.
"We've got a lot of that warm water in the subsurface and under normal circumstances that would make its way to the surface," he said.
"So really we would need a wind event in across the tropical Pacific that would basically keep that water below the surface."
He said it would not be until June that they were able to say with confidence whether or not an El Niño would occur.
Australian model projects 'extreme' El Niño
At this stage, there is still a lot of variation about just how strong the event will be — if it occurs.
The bureau's model suggests ocean temperatures could get up to 2.4 degrees Celsius above normal — warm enough for an "extreme" El Niño to occur.
An "extreme" El Niño is a significant global event.
The last was in 2014–16 and it helped push global temperatures to the hottest on record, with wide-reaching impacts on ecosystems.
Mr Browning said extreme events generally happened when the ocean temperatures were more than 2 degrees Celsius above normal.
But he stressed the bureau's model was still very much the outlier, with projections of its strength unlikely to be reliable until June.
Impacts in Australia
The good news for Australia is that even if an extreme event were to occur it, it would not necessarily equate to extreme drought.
University of New South Wales climate scientist Andrea Taschetto said Australia was more susceptible to impacts from warming in the central Pacific.
"For Australia, what we generally see is that the central Pacific El Niño events are actually moderate events that have a larger impact on Australian rainfall than extreme El Niño events," Dr Taschetto said.
The most recent Pacific El Niño event, known as El Niño Modoki, happened in 2019.
But Dr Taschetto said extreme El Niño events did have big impacts elsewhere around the world.
"It has a big impact for South America, North America, and Asia," she said.
"It is a massive event globally, so it's a very important phenomenon to keep an eye on."
Dry winter on the cards
There is also a growing signal another climate driver linked to dry weather conditions could emerge this winter — a "positive" phase of the Indian Ocean Dipole.
Mr Browning said regardless of whether or not it eventuated, the outlook for winter, which was based on a range of physical parameters, looked dry.
"The whole winter period at this stage [has] quite a strong dry signal," he said.
Ms Stevenson said it meant she would likely have a reduced herd of cattle this season.
"You'd think we would have learnt all the hard lessons from three years of drought, and I think we probably have," she said.
"And I know I've spoken to a lot of neighbours who have already moved a lot of their cattle off to agistment and we've done the same."
Louise Burge from the NSW Farmers Association said recent rains of La Niña would go some way to buffering the impacts of a dry winter, but not for everyone.
"Certain parts of eastern New South Wales, for example, have had good conditions going into this drier phase, but other parts … have had widespread flooding conditions," she said.
"And those flooding conditions have damaged pastures, so there's very little feed now … and those particular farms will have less capacity to meet any challenges a predicted El Niño may bring."
