Driest September on record reshapes expectations for some farm operations

Australia’s driest September on record, aided by a persistent positive anomaly of mean sea level pressure that resulted in cloud-free conditions for most of the country. September was also one of the driest months overall since  observations began in 1900.

• Australian September total rainfall was 70.8% below the 1961–1990 average for September.
• Rainfall in September was below average for most of southern two thirds of the country.
• Rainfall was above average only for parts of eastern Cape York Peninsula  (Queensland) and the far north-east corner of the Top End (Northern Territory).
• Australia’s national area-average mean temperature was 2.43 °C warmer than the 1961–1990 average, the third-warmest on record (since 1910) for September.
• This was the warmest September on record for Western Australia, and the second-warmest September on record for New South Wales, Victoria and South Australia.
• Area-average mean maximum temperature for September was 3.38 °C above average nationally, the second-warmest on record. The national mean minimum temperature was 1.48 °C above average, the eight-warmest on record.
• Mean maximum temperatures for September were warmer than average for most of Australia and over 4 °C above average for large parts in the south of the mainland.
• Mean minimum temperatures were warmer than average for most of Western Australia, South Australia and Tasmania, for southern parts of Victoria, Queensland and the Northern Territory, and for much of northern New South Wales. Mean minimum temperatures were cooler than average for a large area of the southern New South Wales and for areas scattered across northern Australia.

Temperatures gauge

The national mean temperature was 2.43 °C above average for September, the third-warmest on record since national observations began in 1910.

For Western Australia this was the warmest August on record. With the exception of the Northern Territory, all other states were in the top ten warmest Septembers on record.

Australia’s area-averaged September mean maximum temperature was 3.38 °C warmer than average, the second warmest on record for September. Mean maximum temperatures were warmer or much warmer than average for most of Australia. Daytime temperatures were amongst the highest 10% of historical observations (compared with all Septembers since 1910) for South Australia, New South Wales, Victoria, Tasmania, Western Australia excluding the north-eastern part, southern two-thirds of Queensland and large parts in the south and some pockets scattered across the north of the Northern territory. Mean maximum temperatures were the highest on record for most of the southern half of Western Australia, most of Victoria, large parts of central and southern New South Wales and southern South Australia, and for parts of north-eastern Tasmania.  Many stations had their record highest September mean maximum temperature.

New South Wales, Victoria and Western Australia had their warmest September days on record, with statewide mean maximum temperatures 5.07 °C, 3.77 °C and 3.54 °C above the 1961–1990 average respectively. For South Australia and Tasmania this September was the second-warmest on record, while for Queensland mean maximum temperature was the seventh-warmest on record.

The national mean minimum temperature was 1.48 °C above the 1961–1990 September average, the eighth-warmest on record since national observations began in 1910. Mean minimum temperatures were warmer or much warmer than average for Western Australia away from the north, most of South Australia and Tasmania, southern parts of Victoria, Queensland and the Northern Territory, and for much of northern New South Wales. Mean minimum temperatures were amongst the highest 10% of historical observations (compared with all Septembers since 1910) for much of Western Australia, large parts of South Australia extending into south-western Queensland, southern and eastern Victoria, parts of northern Tasmania and pockets of northern New South Wales. Mean minimum temperatures were the highest on record for much of the southern half of Western Australia. Many stations had their highest mean minimum temperature for September on record.

Western Australia had its warmest September nights on record, with a statewide mean minimum temperature 2.33 °C above the 1961-1990 average. For South Australia, mean minimum temperature was the seventh-warmest on record.

Mean minimum temperatures were cooler than average for a large area of the southern New South Wales and for areas scattered across northern Australia.

Temperature table for September 2023

Rank ranges from 1 (lowest) to 114 (highest). A rank marked with ’=‘ indicates the value is tied for that rank. Anomaly is the departure from the long-term (1961–1990) average.