Eastern Australia is experiencing an unexpectedly wet and mild summer, contrary to predictions of a dry, hot season due to an El Niño event. Some forecasts suggest a La Niña might return for the fourth time in five years.
The Bureau of Meteorology (BoM) announced in September that an El Niño event was underway, which typically leads to reduced rainfall across eastern and northern Australia. However, December brought widespread rains, including flooding in some areas.
El Niño usually impacts Australian rainfall primarily through winter and spring, not summer. Despite this, spring saw Australia’s driest September on record, with eastern regions receiving just 7.39mm of rain—only a quarter of the average.
Predicting La Niña for 2024 remains uncertain; models face challenges due to predictability barriers.October also saw below-average rainfall, and although November’s rains improved, the total spring rainfall was still 20% below average.
The El Niño Southern Oscillation (ENSO) involves periodic warming and cooling of Pacific Ocean waters, which influences weather patterns. During El Niño, warming in the central and eastern Pacific typically draws moisture away from Australia. In contrast, La Niña events, marked by cooling in the western Pacific and strengthened trade winds, often result in wetter conditions.
Forecasts for 2024 are uncertain. The US National Oceanic and Atmospheric Administration (NOAA) suggests a potential La Niña following a breakdown of the current El Niño.
However, Australia’s BoM anticipates El Niño-like conditions continuing at least until mid-year. Historically, El Niño years are sometimes followed by La Niña, but the likelihood of another La Niña immediately after an El Niño is debated.
Long-term weather predictions face challenges, particularly from February to May, known as the “predictability barrier,” when models struggle with accuracy.
Future advances in artificial intelligence may improve forecasts, but uncertainties persist. Climate change could also intensify the effects of El Niño and La Niña events, impacting their predictability and severity.