But the Bureau of Meteorology noted that despite the watch being in place, there was no guarantee that a La Niña would form.
There was now a 50-50 chance the weather system would form, as sea surface temperatures had been steadily dropping in the central Pacific since late 2023.
“There are some signs that a La Niña might form in the Pacific Ocean later in 2024,” senior meteorologist Angus Hines said on May 15.
La Niña is a climate pattern involving cool ocean conditions off Australia’s east coast, which historically brings wetter-than-usual conditions for the nation's northern and eastern regions.
The long-range forecast for the period from June to August predicted increased rainfall for some parts of the country, Mr Hines noted.
Higher-than average rain was likely for parts of Western and South Australia, he said, while there were “roughly equal chances” of above- or below-average falls in much of the east.
Record-high global sea surface temperatures, observed each month between April 2023 and April 2024, meant that past experiences of changing conditions in the Pacific might not be reliable, the bureau said.
Current global ocean conditions have not been observed before, making it difficult for meteorologists to accurately predict future weather based on past observations.
The bureau in September declared an El Niño event, which typically brings drier-than-normal conditions and above-average temperatures.
But some parts of Australia still copped a soaking over summer.
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