If a La Nina weather system develops later this year it is likely to be weak, according to the latest climate driver update from the Bureau of Meteorology.

A La Nina can result in increased rainfall and floods across large parts of Australia. The opposite El Nino system was in play from September last year to March, when conditions returned to neutral.

The Bureau then announced a La Nina watch in May, meaning there is about a 50% chance of the weather system developing.

“While some atmospheric indicators such as pressure, cloud and trade wind patterns over the Pacific have been more La Nina-like over the past few weeks, it remains to be seen whether these conditions will be sustained,” the Bureau said today.

Three of seven climate models suggest sea surface temperatures (SSTs) in the tropical Pacific will exceed the La Nina threshold from next month, and another three models forecast SSTs to come close to, or just exceed, the threshold.

“It is possible a La Nina may develop in coming months but if so, it is forecast to be relatively weak (in terms of the strength of the SST anomaly) and short-lived.”

The Indian Ocean Dipole is currently neutral, and most models indicate it will remain neutral for the rest of the year. 

But global SSTs were the warmest on record for each month between April last year and June this year. July and August 2024 were the second warmest on record falling just short of levels recorded last year.

“The sustained nature of this near-record global ocean heat suggests that climate patterns such as El Nino-Southern Oscillation and Indian Ocean Dipole may not necessarily behave or evolve as they have in the past,” the Bureau said.