This year remains on track to become Australia's wettest El Niño year on record, and the first ever with above-average national winter-spring rainfall.
October has been particularly damp thanks to an ongoing outbreak of showers and thunderstorms forecast to affect more than half the country during the next seven days.
Already this week, Sydney has been drenched by more than 100 millimetres of rain, central Queensland has been lashed by severe flash flooding, while outback storms brought destructive winds to Alice Springs.
The focus for storms today is Queensland where an influx of tropical moisture could pave the way for intense cells, and the risk of flash flooding, most likely over inland regions south of Longreach.
Over the central outback today, including around Alice Springs, a drier atmosphere could result in strong downdrafts and gusty winds, while onshore winds bring further showers to the eastern seaboard, extending from Cape York Peninsula south through Brisbane and Sydney to the NSW South Coast.
Stormy weather will then continue to affect Queensland and parts of NSW on Sunday — a pattern which will repeat well into the new week.
This stagnant run of stormy days is somewhat atypical for spring when systems are normally mobile and day-to-day weather is extremely variable.
The current lack of variety, which is more characteristic of autumn, is due to a high-pressure system which stalled in the southern Tasman Sea on Friday.
A high pressure system has planted itself in the Tasman Sea, and will direct moist air onto the eastern seaboard through the week. (ABC News)
The high will remain anchored until at least next weekend, and since winds blow anticlockwise around a high in the Southern Hemisphere, its location is ensuring a humid supply of air off the Tasman and Coral seas.
Storm outbreak to expand across nation
As the wet conditions continue in the east, streams of tropical moisture from the north will also arrive across southern states this week, leading to an expanded zone of showers and thunderstorms from Tuesday.
The exact location of wet weather will shift each day, but modelling indicates most areas of Tasmania, Victoria, South Australia, NSW, the Northern Territory and Queensland can expect at least some rain during the next eight days, with the majority of regions seeing at least 15mm.
For many parts of Queensland and pockets of northern NSW, weekly totals are likely to exceed 50mm, and more than 100mm is possible in the Maranoa and Warrego districts, which would equate to about four times the October average.
Most of Australia can expect rainfall during this week, and totals could easily exceed 50mm for parts of NSW and Queensland. (ABC News)
A wet month against the El Niño grain
The wet October is unfolding despite the Pacific El Niño already being one of the strongest on record, while the Indian Ocean is also entering a dry phase — a combination that has previously been associated with widespread severe drought.
Not only are two major climate drivers now locked into a dry phase, but winter and spring are also when they have historically had the greatest impact.
However, this year is not following the script.
Australia's winter was the wettest for an El Niño year in 35 years, and the national winter-spring mean is on track to exceed the long-term average.
During all 27 previous El Niño years since 1900, none brought above-average winter-spring rainfall, highlighting how unusually wet 2026 is considering the background environment.
So where is all the rain coming from？
There are several factors that could be negating El Niño's influence, and that includes a large blob of warm water in the central Indian Ocean.
But didn't I just say the Indian Ocean was in a dry phase?
The Indian Ocean version of El Niño is called a positive Indian Ocean Dipole, but this climate driver operates across the basin's north between the Horn of Africa and Java.
A warm blob of water in the Indian Ocean may be contributing to a wetter than normal El Niño year. (ABC News)
This year, however, a mass of warm water centred on about 20 degrees south is supplying extra moisture into the air over the Indian Ocean which is then blowing east to Australia in westerly winds high above the surface.
Another factor could be the El Niño warm tongue of water, while exceptional in strength, is centred over the eastern Pacific near South America.
Evidence from past events shows warm tongues closer to the central Pacific, called El Niño Modoki events, can have a greater impact on Australian weather patterns.
More rain ahead in November
Regardless of the precise causes, November is also tipped to be wetter than normal across most of Australia.
Like October, the outlook for November hints at further relatively widespread rain across Australia. (ABC News)
The Bureau of Meteorology's latest outlook for the month shows a strong swing to above median rainfall across most of Western Australia, and a weaker wet signal for the central and eastern inland.
Modelling only favours a drier than average month across the far north-east tropics, Tasmania and along the coast from about Adelaide to Melbourne.
The summer outlook for rain shows no clear signal for most of Australia, meaning the odds of a wetter or drier season are near 50 per cent.