Australia saw a tale of two weather extremes last month, with extremely dry conditions continuing across southern parts of the country as parts of eastern New South Wales recorded the wettest May on record.
The low pressure trough that developed off the coast of NSW on 18 May and lingered for days, led to record high rainfall in numerous locations throughout the Hunter and mid-north coast.
Multiple weather stations experienced daily downpours exceeding 200mm, with many breaking monthly and daily rainfall records for May, according to the Bureau of Meteorology’s climate summary.
Bellingen’s Promised Land weather station recorded 802mm of rain for the month, more than twice its average. The NSW town, located about halfway between Sydney and Brisbane, also set a record for the highest daily rainfall for May, with 337mm on 22 May.
Record daily totals for May were also set at Williamtown RAAF base (149mm on 23 May) and Morisset (126mm on 19 May) in the Hunter region.
May is usually a dry time of year for northern and central Australia. But several places in the Kimberley and Northern Territory experienced heavy falls of 100mm or more in 48 hours, according to the BoM.
Meanwhile the dry spell continued across southern Australia, with rainfall in Victoria and South Australia more than 70% below average for the month. Victoria experienced its driest May since 2005, according to the BoM. It was also the state’s second warmest May on record.
The persistent dry conditions have contributed to a heightened winter bushfire risk for South Australia and Victoria.
Maximum temperatures in May were 1.08C above the 1961-1990 average, BoM data showed, and minimum temperatures were up 0.6C.
“If you look at the weather charts, we’re seeing a subtropical ridge sitting south of Australia close to the start of winter, and that’s normally a pattern that you would expect to see in summer,” said climatologist Darren Ray, a researcher based at the University of Adelaide.
South Australian agricultural regions were experiencing “extreme to exceptional drought”, he said, with some areas recording their lowest “standardised precipitation index” values – a measure of drought – for the past 12 to 18 months, in records that dated back to 1880.
The wet and dry extremes were part of the same larger-scale system, with high pressure over southern Australia encouraging moisture streams off the east coast, said associate prof Ailie Gallant, who researches drought and rainfall extremes at Monash University.
“This is an unusual situation. A lot of farmers in particular are really feeling the pinch right now, and unfortunately, with these types of events, we don’t know when it’s going to end,” she said. “The best we can do is look on the horizon for the kind of weather systems that will promote heavy rainfall.”
The contrasting conditions – large areas in drought while others experienced record-breaking rain – were “quite unusual”, according to Dr Kimberley Reid, an atmospheric scientist at the University of Melbourne.
Reid said drought in Australia was usually due to the lack of heavy rainfall, not just a decrease in average rain. “One to five days of rain [annually] can be the difference between a drought, and not a drought for southern parts of Australia.”
There had been a lot of “frustratingly settled weather” and “clear skies” in southern Australia, she said.
Nationwide, autumn average temperatures were 1.41C above the 1961-1990 average, the fourth highest on record, according to the BoM. Victoria had its warmest ever autumn, New South Wales and Western Australia second-warmest, and South Australia its third-highest.
“One thing that is clear is that 2025 will likely be the one of the warmest years on record, and so will the next few years,” Reid said. “If we continue to burn fossil fuels – whether we burn them here at home or export them elsewhere to be burnt overseas – we’re going to keep seeing temperature records fall year on year if we don’t change our behaviour.”
