Australia experienced its second-hottest September on record last month, driven by global heating and an intensifying El Niño system that combined to push minimum and maximum temperatures well above long-term averages across the continent. Bureau of Meteorology data showed that average temperatures for the month reached 2.71°C above the 1961 to 1990 baseline, while minimum night-time temperatures were the hottest for any September since records began in 1910, according to theguardian.com.
Continental Heat and Record Minimum Temperatures Across States
Every state recorded average temperatures ranking in its top five warmest Septembers, while the Northern Territory registered its sixth hottest. Minimum temperatures across the continent rose 2.52°C above average, narrowly eclipsing the previous September record of 2.51°C set in 2023. Data cited by theguardian.com confirms that Australia has not recorded a below-average mean temperature for September since 2004, and long-term global heating has warmed the continent by more than 1.5°C since 1910.
In New South Wales, 45 locations recorded their warmest Septembers on record. Meanwhile, South Australia sweltered through extreme early spring heat before a cool change arrived, with Adelaide reaching 34.4°C on Tuesday—its hottest September day in 65 years, according to news24.com.au. Hobart reached 23°C, Canberra hit 25°C at roughly eight degrees above average, and Darwin recorded 33°C.
Alpine Snow Depths Falling to Zero in Kosciuszko National Park
High-altitude regions suffered severe impacts from the unseasonal warmth, with several ski resorts closing early after a warm and rainy winter. Monitoring data from Snowy Hydro’s gauge at Spencers Creek in Kosciuszko National Park showed that snow depth fell to zero during September for the first time since monitoring began in 1954, theguardian.com reported. At Thredbo, where temperature records span 59 years, the average daily minimum for September rose above freezing for the first time at 0.1°C, alongside a record-high September day of 16°C. Victorian alpine locations including Mount Buller, Falls Creek, and Mount Hotham also recorded their highest monthly maximum temperatures on record.
Eastern Dryness Contrasting With Western Rains in September
Rainfall patterns varied sharply across the country during the month. Eastern Australia recorded its second-lowest September rainfall since national records began in 1910, reneweconomy.com.au reported. Area-averaged rainfall across eastern Australia was down about two-thirds from the long-term norm at 8.32 millimetres, trailing only the 7.39mm average recorded in September 2023. New South Wales experienced its fourth-driest September since observations began in 1900, while Victoria recorded its sixth-driest September due to persistent high-pressure systems over the southeast.
In stark contrast, Western Australia posted its second-wettest September on record and its wettest since 1904, with area-averaged rainfall reaching 147% above the historical average. In Tasmania, parts of the north-east and Flinders Island received less than 20% of their average September rainfall, prompting farmers to reduce stock numbers as feed and dam levels diminished, according to Tasmanian Country.
El Niño Strengthening in the Tropical Pacific
Dr Linden Ashcroft, a climate scientist at the University of Melbourne, stated that climate change remains the primary driver behind the persistent heat and seasonal creep, where winter ends earlier and spring starts sooner. Bureau senior climatologist Dr Simon Grainger noted that persistent high-pressure systems kept days warm and dry across the southeast, while an intensifying El Niño climate system in the tropical Pacific contributed significantly to the month’s temperature and rainfall anomalies. US National Oceanic and Atmospheric Administration data posted on the Climate Reanalyzer website shows that sea-surface temperatures in the El Niño 3.4 region have exceeded previous record highs set in 2015, two months earlier than that peak, according to reneweconomy.com.au.
Questions Regarding Regional Climate Impacts
- Adelaide reached 34.4°C on Tuesday, marking its hottest September day in 65 years, according to news24.com.au.
- Eastern Australia averaged 8.32 millimetres of rainfall, which is about two-thirds below the long-term norm and the second-lowest since 1910, reneweconomy.com.au reported.
- Monitoring at the Snowy Hydro gauge started in 1954, and September marked the first time snow depth fell to zero during the month since records began, theguardian.com noted.
- Area-averaged mean temperatures across Australia were 2.71°C above the 1961 to 1990 baseline, according to Bureau of Meteorology figures cited by theguardian.com.
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