Aussies warned to prepare in wake of major weather announcement set to affect millions

If a La Niña event is formally declared in the coming months, it would be a significant moment in the history books.

A woman pictured in Sydney rain with a graph of the La Niña watch alert meter.
There is roughly a 50 per cent chance another La Niña weather event will occur for Australia this year. Source: Getty/BoM

An unprecedented weather event is edging closer to becoming a reality as conditions ripen for yet another wet La Niña cycle, that will, if declared, see soggy conditions return across the nation's east coast later this year.

The declaration would mark the first time in history Australia has seen an El Niño or La Niña weather event five years in a row.

The BoM released its latest update this week revealing that there are "some early signs a La Niña" might form in the Pacific Ocean later in 2024, and, "a result, the ENSO Outlook has shifted to La Niña Watch".

The official designation will have meteorologists and climatologists watching on closely. From here, according t the Bureau, there's about a 50 per cent chance the system will eventuate.

Commuters seen donning rain coats and umbrellas in wet weather, as the BoM declares Australia is on La Niña watch.
If La Niña is declared, it would be the fourth in as many years and mark five consecutive years of either a La Niña or El Niño event. Source: Getty

Speaking to Yahoo News Australia, Climate Professor Shayne McGregor from Monash University said there are a "couple of things" that have led us to this moment.

The first being the history of El Niño events — a cycle that's just wrapped up — being more often than not followed by a La Niña. "This suggests there is an increased chance of a La Niña event occurring relative to a neutral/normal year," he earlier told Yahoo.

As well, McGregor explained, there are "temperature signals in the subsurface ocean" that are consistent with the beginning of a La Niña event. "However, it is important to note that the signs of an ending El Niño event look like the beginning of a La Niña, so there is some ambiguity here."

If La Niña were to be declared, it would mean an increased chance of wetter-than-normal conditions from July to November, when the "strongest impacts" of the weather events are felt. "There would also be a reduced chance of having particularly dry conditions during these months," he said.

A weather map by Weatherzone depicting conditions readying for La Niña.
The strongest indicator yet a La Niña event is on its way has been announced. Source: Weatherzone

According to the BoM's update on Tuesday, the ENSO Outlook will most likely remain in its neutral phase until at least July. "It is important to emphasise that early signs of La Niña are most relevant to the climate of the tropical Pacific, and that the long-range forecast for Australian rainfall and temperature provides better guidance for local climate," it said in a statement.

Early indicators suggesting that La Niña could return in the second half of 2024 include the fact that sea surface temperatures (SSTs) in the central Pacific have been steadily cooling since December 2023, supported by a significant amount of sub-surface cooling in the central and eastern Pacific.

In the wake of the announcement, authorities are urging Aussies to be aware of the outlook change, with those in flood-prone areas being told to prepare ahead of the potential declaration.

NSW SES Assistant Commissioner Nicole Hogan said now is the time to review emergency plans. “While storms and flash flooding can happen at any time, if a La Niña weather pattern does return later this year it will be the fourth in as many years and we want the community to remain vigilant,” she said.

SES volunteers standing in floodwaters, as the the BoM declares Australia is on La Niña watch.
The NSW SES has urged Aussies to be prepared in the wake of of the ENSO Outlook change. Source: NSW SES

“La Niña weather events can bring above average rainfall, as we saw over the last couple of years with record flooding to many parts. It is important to know your storm and flooding risk, have a plan in place, get your home ready, be aware of what you will do if disaster strikes, and look out for one another.

“Clean your gutters, downpipes and drains, secure and put away any loose items around your backyard and balcony, and trim trees and branches that could fall onto your home."

Australians were battered by La Niña cycles in 2021, 2022 and 2023. In April, the BoM formally declared the end of the 2023-24 El Niño event.

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