Australia has had its second-hottest September on record, according to the Bureau of Meteorology's monthly climate summary.
The national area-averaged mean temperature was 2.71C above the 1961-1990 average, the highest September figure since 2013 and the second-highest since national observations began in 1910.
Every state and territory recorded a September mean temperature inside the top ten on record.
The national mean maximum temperature was 2.90C above average, the third-highest on record, with all states and territories in the top ten. The mean minimum was 2.52C above average, which is the highest on record for September.
Western Australia and South Australia both set record September minimum temperatures: 3.19C above average in the west, surpassing records set in 2023 and 2024, and 3.24C above average in South Australia, surpassing a record set in 2013.
Rainfall is where the month divides. The national area-averaged total was 17 per cent below the 1961-1990 average.
Western Australia had its second-wettest September on record, with rainfall 147 per cent above average. New South Wales had its fourth-lowest September rainfall since records began in 1900.
Rain was above average across much of Western Australia, western South Australia, far north Queensland and parts of the Northern Territory, and below average across most of the east and south-east.
Temperature was less divided than rain. Mean maxima sat in the highest 10 per cent of all Septembers for most of the country, with records in parts of northern and eastern Tasmania and small areas of New South Wales, Queensland and Western Australia. Cape York Peninsula was the exception, with maxima in the lowest 10 per cent.
The national rainfall figure deserves a moment's attention, because of the method by which it is made. It is an area-average: every part of the continent contributes its rain, in proportion to its size, to one number.
That number this September is 17 per cent below average. The west was 147 per cent above it. New South Wales was inside its four driest Septembers in 126 years. Neither of those conditions is 17 per cent below average, and nowhere in Australia had the September that the national figure describes.
The Department of Unnecessary Research has established where the 17 per cent occurred. It occurred in the calculation. Australia, the area-averaged entity, had a mildly dry September. Australia, the landmass, did not have one anywhere.
This is a more capable instrument than it looks. A country may be given any weather at all, provided its extremes are arranged to cancel, and a sufficiently large country can be made average by definition.
The bureau's temperature figures escape the problem only because the heat was general. Second-hottest nationally, top ten in every state and territory: that is a figure with a location, which is to say a real one.
The rain has no such address. It fell, in near-record quantity, on one side of the continent, and failed to fall, in near-record quantity, on the other. The average of the two is a month that Australia had and no Australian attended.