Australia has just sweated through its second-hottest summer since national records were first kept in 1910, while it was the hottest summer on record in Western Australia.

• Australia as a whole was 1.89°C above the long-term average in the summer of 2024/25 (based on the 30-year period from 1961-1990).
• That put this summer just behind the summer of 2018/19 (which was 2.11°C above the long-term average, and which kicked off Australia’s hottest year on record in 2019).

Image: Summer mean temperature anomalies for Australia since 1910. Source: BoM.

In terms of key statistics from the states:

• Averaged across the state, WA had a mean temperature anomaly in the summer of 2024/25 that was 1.93°C above the long-term average. As mentioned above, that made it the hottest summer on record.
• Western Australia's 2nd-hottest summer was the previous one in 2023/24, when temps were 1.89°C above the long-term average.
• South Australia had an even larger temperature anomaly than WA across the 2024/25 summer, with statewide temps that were 2.48°C above the long-term average, however that only made it the second-hottest summer on record.

Image: Summer mean temperature anomalies for Western Australia since 1910. Source: BoM. 

Why such a hot summer?

Several factors contributed to the hot summer of 2024/25.

One factor was the delayed onset of the monsoon in northern Australia, which prevented cloud from moderating high temperatures in the region.

Another influence on Australia’s weather was the Southern Annular Mode (SAM), which refers to the band of westerlies that blow in the mid-to-high latitudes of the Southern Hemisphere.

The SAM spent more time in a negative than a positive phase over summer, which means the westerlies were slightly further north. This generally means less summer rainfall for the southeastern corner of the country, which in turn tends to deliver warmer temperatures.

Another factor was consistently warmer-than-usual sea temperatures around the country, the effect of which is bit like a hot water bottle on Australia's weather over the length of a season.

And of course, the underlying warming of the climate played a part.

Australia has now experienced 13 summers in a row with above-average temperatures nationwide across the entirety of the season.