https://www.abc.net.au/news/2024-07-04/australias-highest-air-pressure-recorded-...In short:

Climate change to fuel stronger highs
It took more than half a century to break Australia's air pressure record, but if weather trends continue, the next challenge could occur in a much shorter time span.
Data from the BOM shows both the density and intensity of highs has increased since 1950 around Australia, meaning not only are high pressure systems more frequent, they are also slowly gaining in strength.
The weather station at Sheffield in Tasmania reported a pressure of above 1044.3 hectopascals on Thursday morning.
If confirmed it beats the previous Australian record from 1967.
It is contributing to extreme low overnight temperatures over south-east states and a lengthy stretch of showery days along the eastern seaboard.
What's next?
The Bureau of Meteorology expects sea levels over south-east Australia will drop accordingly.
Unprecedented high atmospheric pressure is currently being observed across south-east Australia, including a preliminary new national record measured in Tasmania this morning.
The weather station at Sheffield reported a pressure of 1,044.6 hectopascals (hPa) at 10:30am, which if confirmed beats the previous Australian record of 1,044.3hPa at Launceston on June 7, 1967.
The potential record is slightly contentious due to changing observation frequencies and techniques between now and 1967.
However, the high looks likely to peak again near 1,044hPa early Saturday, providing another opportunity for a record before the system weakens from Sunday.
The abnormal pressure is having a significant impact on the nation's weather, including extreme low overnight temperatures over south-east states and a lengthy stretch of showery days along the eastern seaboard.