• A record-breaking heatwave occurred throughout mid-September around the Eyre Peninsula.
  • Some areas reached temperatures over 18°C above average.

Extreme temperatures 10°C to 20°C above average occurred over large parts of South Australia from 16th to 19th September 2023. At Ceduna, the temperature reached 39.8°C on 17th September, which is the highest recorded September temperature in Ceduna since records began. This temperature was 18.2°C above the September average temperature. The maximum September temperature record was also broken at Port Augusta, where the temperature reached 38.4°C.

Winds coming from the north resulted in dry and warm air blowing in from the northern parts of Australia into south- east Australia. These northerly winds were in part due to a stationary high-pressure system off the east coast of the country. This hot air from the central Australian desert then drove the already warm landscape into the extreme heatwave conditions that occurred during this event.

Figure 1: Maximum temperature anomaly for 17th September 2023. The temperatures were over 12 degrees above September averages. Source: Bureau of Meteorology.
Figure 2: Daily maximum and minimum temperatures recorded by the Port Augusta airport weather station throughout September 20231. Note that there was no data on the 4th of September. Source: Bureau of Meteorology.

The hot weather in South Australia also extended to New South Wales and Victoria. For example, on 17th September the Sydney marathon took place in over 30°C heat, with 40 people requiring treatment by paramedics.

Such unseasonably high temperatures are part of a larger trend in south-east Australia, where heatwave events are becoming more frequent, more intense, and occurring earlier than usual as a result of human-caused climate change.

Although South Australians are well adapted to hot weather, these events are concerning due to their negative impacts on agriculture, human health as well as natural and urban environments.

Research contacts:

Daniel Johnston, Daniel.Johnston@anu.edu.au Dhruv Bhagtani, dhruv.bhagtani@anu.edu.au Jarrad Rowe, roweja@student.unimelb.edu.au Dr Claire Vincent, claire.vincent@unimelb.edu.au