The infamous variability of spring weather across southern Australia will be on full display this week. South-eastern states are set to experience temperatures up to 10 degrees Celsius above average, while Western Australia braces for another bout of wintry showers and storms. This weather pattern is expected to shift eastward, sparking the first thunderstorm outbreak of the season in parts of South Australia, Victoria, and New South Wales on Sunday and Monday.
A major rain event is predicted across eastern Australia starting Tuesday, with the potential to deliver more than a month’s worth of rain to areas within the Murray Basin. This development follows a particularly wet winter in the region, hinting at a spring season that could continue the trend.
Australia’s Heat Engine Ignites
Spring is a season of transition, where tropical and polar air masses vie for dominance across the mid-latitudes. Over the weekend, tropical air is expected to gain ground over south-eastern states, driven by a northerly airstream originating from Australia’s “heat engine”—the northern inland of Western Australia. This region is known for producing some of the hottest weather that impacts much of the nation.
Inland parts of South Australia are forecast to exceed 30°C for the first time since April, with capital cities also expecting their warmest weather since autumn. Adelaide, Melbourne, Canberra, and Sydney are all set to experience significant temperature highs, marking a stark contrast to the cooler months.
- Adelaide: 25°C on Saturday, highest since May 13.
- Melbourne: 22°C on Sunday, highest since May 13.
- Canberra: 22°C on Sunday, highest since May 7.
- Sydney: 27°C on Monday, highest since April 21.
However, this burst of heat will be short-lived. Fresh to strong northerly winds could lead to raised dust in South Australia and the Mallee on Saturday, along with damaging gusts along the Victorian ranges on Sunday. True to spring’s unpredictable nature, a series of polar air pulses will soon follow, potentially slashing temperatures by as much as 15°C by midweek.
Stormy Skies Spread from WA to Eastern States
Just days into spring, the seasonal wet outlook is already manifesting. After the wettest winter in 29 years in south-west WA, rain returned on Friday, with Perth receiving up to 30 millimeters by sunset. Showers and storms are expected to continue across western and southern WA before the system weakens as it moves eastward on Sunday.
Despite the front’s weakening, its interaction with warm air over south-east Australia will likely trigger a band of showers and thunderstorms from the central interior down to Tasmania. Enhanced by a jet stream blowing at speeds of up to 250 kilometers per hour, these storms could bring damaging winds, hail, and heavy rain.
While Melbourne may see early showers on Sunday, the greatest storm risk will be over northern suburbs due to their proximity to the Great Dividing Range. The combination of strong winds and potential downdrafts poses a significant threat, with some storms potentially reaching destructive intensities.
Widespread Heavy Rain and Drought Relief from Tuesday
The upcoming storms are merely a prelude to a larger weather event. A second front is expected to hit the WA south coast on Sunday, moving east to collide with tropical moisture and generate widespread rain across south-east states by Tuesday and Wednesday.
Rainfall could reach up to 50mm on the NSW and eastern Victorian ranges, with the southern Murray Basin likely seeing 10 to 30mm, offering further drought relief following significant winter rainfall. However, the potential formation of a low-pressure system remains uncertain, which could lead to even heavier falls in parts of Victoria or southern Queensland.
Negative IOD Now Strongest in Three Years
A negative Indian Ocean Dipole (IOD) is contributing to the wet conditions. This climatic phenomenon, which began in late July and intensified through August, is now one of the strongest on record, comparable to similar events in 2010, 2016, and 2022.
The latest IOD index was calculated at -1.28, well below the negative threshold of -0.4.
While a negative IOD typically signals a wetter spring, experts caution that the strength of such climate drivers does not directly equate to specific weather outcomes. Thus, while a wet spring is anticipated, it does not guarantee record-breaking rainfall.
As the week unfolds, Australians will be watching the skies closely, prepared for both the warmth of spring and the potential for severe weather. The unfolding weather patterns will not only test the resilience of communities but also provide critical insights into the ongoing impacts of climate variability in the region.
