Spring is set to be wet and warm in eastern Australia, according to the Bureau of Meteorology’s seasonal outlook.
Key points:
- Spring rainfall is likely to be above average in much of the east
- Maximum temperatures are likely to be above average for the northern tropics and far south-east
- Large parts of the eastern tropical Indian Ocean are warmer than average
But below average rainfall is likely for parts of coastal Western Australia and south-west Tasmania.
“Virtually all of eastern Australia is looking wet,” the BOM’s head of operational climate services Andrew Watkins said.
“With a negative Indian Ocean Dipole, we’ve got warm ocean temperatures near Western Australia, and that’s pumping a lot more cloud and moisture across the continent and giving wetter than average conditions.”
That is despite the ENSO climate driver being in neither a La Niña state (which would favour rain) nor an El Niño state (which would favour drought).
“We have some signs that we could be heading towards La Niña, though the forecasting models have been backing off a little bit of late,” Dr Watkins said.
“Typically, even if we don’t get to La Niña levels, that would help enhance rainfall in parts of eastern Australia.”
Warmer nights on the way
Maximum temperatures through spring are likely to be above average for the northern tropics and the far south-east, while below average daytime temperatures are more likely for other areas of southern Australia and up into southern Queensland.
At night, above average minimum temperatures for September to November are very likely for almost all of Australia, except for the southern part of Western Australia.
The soggy spring follows on from a wet winter in much of the country, particularly in south-west Western Australia.
“Nationally, we’ve seen the wettest winter since 2016,” Dr Watkins said.
“In the south-west, they’ve had a good old-fashioned winter with a continuing series of cold fronts bringing pretty consistent rainfall, particularly during June and July.
Warm winter despite rain, snow
Across tropical Northern Australia, it has been very warm through winter, with Darwin having its earliest 35-degree day on record.
“Australia’s average winter temperature is also expected to be one of the 10 warmest on record — as much as it hasn’t felt it at times, particularly in the south,” Dr Watkins said.
Typically during a negative Indian Ocean Dipole, Australia sees cooler than average temperatures, but the BOM says Australia’s temperature and rainfall variability are also influenced by global warming.
Australia’s climate has warmed by 1.44 degrees Celsius between 1910 and 2019 and southern Australia has seen a reduction of 10-20 per cent in cool season (April-October) rainfall over the last few decades.
Despite the warm winter, alpine regions have had a close-to-average snow season, with snow depths at the benchmark Spencers Creek gauge peaking at 183.6 centimetres on of July 29, slightly below the long-term maximum snow depth of about 195cm.
“Not a bad ski season if you can get there,” Dr Watkins said.
“It’s fairly typical for a negative Indian Ocean Dipole.
“But also, we’ve had negative Southern Annular Mode at times, so our weather systems have been that bit further north more generally, and that does typically give you more snow cover.”