Sunshine in sight? La Niña weather pattern to end in early 2023, BoM predicts

Third consecutive La Niña, which has brought widespread rain and flooding to eastern Australia in 2022, is likely to end by next February, models show

Sunny skies may finally be on the horizon, with Bureau of Meteorology modelling suggesting an end to the La Niña weather pattern early next year.

The long run of wet weather over many parts of Australia has been driven by three consecutive years of La Niña events, which result in increased rainfall across northern and eastern Australia.

The Bureau’s latest climate driver update, released on Tuesday, forecasts a return to a neutral phase of the El Niño-Southern Oscillation, a cycle in which winds and sea-surface temperatures vary over the tropical eastern Pacific Ocean. The majority of the BoM’s models indicate a “return to ENSO-neutral in early 2023”.

@BOM_au is predicting the La Nina will be shallow, with conditions in the Pacific reverting to neutral conditions by late 2022 - early 2023...

— Peter Hannam (@p_hannam) October 25, 2022

Assoc Prof Shayne McGregor, of Monash University and the ARC Centre of Excellence for Climate Extremes, said a normal La Niña or El Niño event would usually peak around Christmas and rapidly decay in the following months.

BoM models show that Pacific sea-surface temperatures will no longer meet La Niña thresholds by February. “It suggests … the event might peak a little bit earlier than the normal December–January [period],” McGregor said.

During a La Niña, strong trade winds blow west across the Pacific Ocean. Warm surface water is pushed towards Asia and the seas north of Australia, resulting in higher rainfall than normal across the country’s north-east. The weather event has the inverse effect across the Pacific, with 60% of the US declared to be in a designated drought zone last week.

In an El Niño, the trade winds weaken or reverse, leading to warmer surface water in the central Pacific, and less moisture north of Australia. El Niño events are often associated with severe bushfire seasons, although the 2019-20 black summer bushfires occurred in a neutral year.

Historically, around half of all years have been classified as ENSO-neutral, a phase that marks the transition between the La Niña and El Niño. “There are typically two neutral years for every El Niño and La Niña,” McGregor said.

“Quite often an El Niño will transition [directly] into a La Niña, but La Niñas don’t typically transition straight into El Niño,” McGregor said. “Looking at the statistics of past events, it does suggest that we would more likely have a neutral event next year.”

Until the ENSO enters a neutral phase, “we’ll still be expecting more rainfall than normal, unfortunately,” he added.

Extreme La Niña and El Niño events are projected to increase as the planet warms.

Indian Ocean dipole to become neutral

Another climate driver, the Indian Ocean dipole, is also forecast to swing into a neutral phase. The IOD has been negative for the past two years – the first time two consecutive such events have occurred since reliable records began in 1960.

A negative IOD is usually associated with above-average spring rainfall for most of central and eastern Australia. An extreme positive IOD intensified the 2019-20 bushfires.

“Models indicate that the negative IOD is likely to persist into late spring before rapidly decaying,” the BoM said. “When La Niña and negative IOD conditions combine, the likelihood of above average rainfall over Australia is further increased, particularly for the eastern half of the continent.”

Australia’s climate warmed by around 1.47C between 1910 and 2020. The BoM has also noted “a trend towards a greater proportion of rainfall from high-intensity short-duration rainfall events, especially across northern Australia”.


Donna Lu

The GuardianTramp

Related Content

Article image
Australia could swing from three years of La Niña to hot and dry El Niño in 2023
Bureau of Meteorology climate models indicate sea-surface temperatures in the Pacific may exceed El Niño thresholds by June

Peter Hannam

03, Jan, 2023 @2:00 PM

Article image
Australia records fourth-warmest year in 2020, despite La Niña
Climate scientist says another top 10 year is a ‘no shit, Sherlock’ moment, as temperatures across the country were 1.15C above average

Graham Readfearn

01, Jan, 2021 @6:09 AM

Article image
Famous Australian beaches vulnerable to severe coastal erosion caused by La Niña
Researchers say erosion of beaches along south-east coast – including at tourist hotspot Noosa – is significantly affecting local biodiversity

Donna Lu

09, Feb, 2023 @4:00 PM

Article image
More floods forecast for Australia’s east as La Niña weather pattern lingers
Bureau of Meteorology climate report points to big wet in NSW and Queensland extending for months

Peter Hannam

24, May, 2022 @11:00 PM

Article image
Could a fourth La Niña follow Sydney’s record-breaking rainfall?
Another week of torrential rain has obliterated the previous annual record for highest rainfall. What’s behind the east coast’s latest drenching?

Graham Readfearn

08, Oct, 2022 @7:00 PM

Article image
Australian La Niña dampens fire risk but threatens summer crops
Confirmation of a third La Niña event is a relief for those living in bushfire areas but high rainfall brings its own troubles

Calla Wahlquist

13, Sep, 2022 @5:30 PM

Article image
Bureau of Meteorology declares third La Niña is officially under way for Australia
East coast communities prepare for more rain and floods as they enter relatively rare third year of climate event

Peter Hannam

13, Sep, 2022 @5:06 AM

Article image
Heavy rain forecast for Australia’s east coast as third La Niña brings fears of renewed flooding
Widespread thunderstorms will make Thursday the ‘wettest day’ for NSW during public holiday honouring the Queen’s death

Caitlin Cassidy

20, Sep, 2022 @8:20 PM

Article image
Floods and warm weather perfect storm for Japanese encephalitis outbreak, researchers warn
Modellers say those within 4km of an infected piggery potentially vulnerable, meaning 740,546 people at risk of mosquito-borne virus

Melissa Davey

19, Oct, 2022 @3:00 PM

Article image
NSW braces for more flash flooding as wet weather lashes Australia’s east coast
‘Very significant’ weather systems to move across state this week, with warnings also for northern Victoria and southern Queensland, bureau says

Caitlin Cassidy

04, Oct, 2022 @1:10 AM