Australia has had one of its wettest springs on record as the country has endured its third consecutive La Niña event.
But with La Niña finally on the decline, the wet weather should ease in the coming weeks.
Although some forecasters are already predicting a return of El Niño next year – bringing the risk of bushfires and droughts – experts told The New Daily that bold predictions for the coming months should be treated with caution.
What is El Niño?
El Niño is the warm phase of the El Niño-Southern Oscillation and is associated with hot weather and droughts.
The Bureau of Meteorology told TND that neutral conditions would likely return in coming months but warned against long-term forecast predictions.
“Outlooks indicate neutral El Niño–Southern Oscillation (ENSO) levels – neither La Niña nor El Niño conditions are likely in the coming months,” it said.
“However, given that forecasts made in summer for the following winter have lower levels of accuracy than those made at other times of the year, it is too early to make solid inferences and a more confident outlook will be possible late in summer and early autumn.”
Forecaster Weatherzone agreed it was too early to declare a looming El Niño with any certainty.
“[O]verall, a drying trend relative to average is now looking likely across much of the country,” it said on its website.
“Whether we see the opposite of La Niña – El Niño – with its signature hot, dry summers in the near future is not yet clear.”
Meteorologist Dr Milton Speer told TND that while El Niño was certainly a possibility, and more likely than a fourth La Niña, we won’t know for sure until the middle of next year.
“There’s a predictability gap in autumn, where you don’t know what’s going to happen for the next spring and summer, until you get over it,” he said.
“If you’re going into an El Niño, you begin to see it around June.
“I would be very unusual for us to go into a fourth La Niña … you don’t normally get two in a row, or three in a row, let alone four. So it’s much more likely to be either neutral or swing into an El Niño next year, just in terms of odds.”
There is some computer modelling from overseas that suggest that El Niño may return in 2023.
The graph below shows the likelihood of an El Niño occurring according to modelling from US Climate Prediction Centre and Columbia University’s International Research Institute for Climate and Society.
It’s important to note that these organisations use a more relaxed threshold than Australia’s Bureau of Meteorology for identifying La Niña and El Niño.
The bars on the graph above represent the probability of La Niña (blue), El Niño (red) and neutral conditions (orange) occurring in the tropical Pacific Ocean during each of the next nine overlapping three-month periods.
The graph shows that La Niña has a 77 per cent likelihood of remaining in place until February.
Neutral conditions then become more likely than La Niña from late summer until the middle of 2023.
According to this data, El Niño becomes the most likely state for the Pacific Ocean late in the winter.
This is the first time in about three years that the monthly outlook has favoured El Niño as the most likely category in the Pacific Ocean.
What are the effects of an El Niño in Australia?
Lower rainfall
- El Niño increases chances of below-average rainfall through winter and spring in much of Australia, especially the north and east
- El Niño does not always mean drought, but nine out of the 10 driest winter/spring periods happened in El Niño years
- Australia’s severest droughts – 1982-83, 1994, 2002 and 2006 and 2015 were all associated with El Niño
- Since 1900, El Niños delivered winter/spring rainfall 28 per cent lower than the long-term average.
Temperature extremes
- Warmer-than-average weather, particularly in southern Australia and particularly in the second half of the year. Decreased cloud cover increases surface heating and assists to keep rainfall low
- Background warming of the atmosphere has made El Niño years warmer since the 1950s, according to the Bureau of Meteorology
- In warmer months, El Niño can cause fewer slow-moving “blocking” high-pressure systems, worsening heat extremes for cities such as Adelaide and Melbourne with an increase in extreme hot days and heatwaves further north
- Frost increases in El Niño years in cooler months in eastern Australia because clearer skies contain less daytime heat and lead to reduced minimum temperatures
- Between 15 and 30 per cent more frost days in El Niño years than average in northern Victoria and southern NSW, affecting agriculture
- Australia’s record low temperature of -23 degrees at Charlotte Pass, NSW, on June 29, 1994, occurred during a strong El Niño.
Increased bushfire risk
- El Niño droughts dry the bush and have led to disasters, including the 1983 Ash Wednesday bushfires that killed 71 people in Victoria and South Australia.
Disrupted tropical weather
- Fewer tropical cyclones, especially for Queensland
- Later onset of northern monsoon rains
- Below-average wet season rains early in the season, with average rain later in the season.
Reduced winter snowfall
- The four lowest recorded peak snow depths in Australia’s alpine country occurred in El Niño years, including severe drought years in 1982 and 2006.
