'Emphatic': Odds point to big dry expanding across eastern Australia
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'Emphatic': Odds point to big dry expanding across eastern Australia

Fire authorities, farmers and even water storage managers may be in for even more trying times as odds increase for the drier and hotter conditions across eastern Australia to continue deep into spring.

Places such as Sydney are already on track for record-breaking July temperatures amid the lowest rainfall in decades.

The Bureau of Meteorology's latest three-month outlook, updated on Thursday, points to more of the same for months to come.

There's no sign of a let-up for most of eastern Australia's drier and hotter than average weather.

There's no sign of a let-up for most of eastern Australia's drier and hotter than average weather.

Photo: Johnathan Carroll

While the August-October forecast suggests odds favour a drier and hotter than normal stint for mainland south-eastern Australian, the chances are particularly strong for next month alone, Jonathan Pollock, a bureau climatologist, said.

"It's unusual to have such widespread emphatic odds," Mr Pollock said.

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"Everywhere south of Armidale [in north NSW] has a greater than 80 per cent chance of below-average rainfall," he said.

So far in July, rainfall totals in NSW have been less than half the norm for much of the state. For the first six months of the year, they were also half the average, marking the driest start to a year since 1986, the bureau has said.

For Sydney alone, this month is on track to being the driest July since 1995 on current forecasts, with just 9.8 millimetres so far collected at Observatory Hill. A typical July would have almost 10 times that, at 96.6 millimetres.

Record warmth

The standout for Sydney, though, may be its daytime temperatures. On Thursday, the mercury climbed above 20 degrees for the eighth day this month, with five more forecast by July 31.

The record number of such days is 12, in 2013. Even if the record is not broken, there's a fair chance the bar will be lifted for maximum temperatures, also set 2013 at 19.5 degrees. A typical July averages 16.4 degrees.

As Fairfax Media reported on Monday, authorities have already brought forward the start of the official fire season for parts of north-eastern NSW.  Some other regions, where the season would typically start in October, are likely to be brought forward to September.

Farmers wilt

Mr Pollock said parts of the state had soil moisture levels down to 1 per cent of normal conditions, hammering farmers.

Sheep hunt for grass on a farm near Manilla, not far from Tamworth, in northern NSW.

Sheep hunt for grass on a farm near Manilla, not far from Tamworth, in northern NSW.

Photo: Peter Hardin

Among other things, it also means rainfall when it comes would likely be first soaked up in the soils rather than ending up in dams and rivers.

"That's bad news for water storage," Mr Pollock said.

The reason for the lifting of odds for poor rainfall and warmer-than-usual conditions is partly a cooling of waters off Western Australia of late. This shift tends to reduce moisture over the continent.

There have also been weaker and fewer rain-bearing cold fronts extending into south-eastern Australia amid generally relatively weak westerly winds, Mr Pollock said.

El Nino lurks

While the bureau's outlook only covers the coming three months, there are few signs the pattern will be breaking up soon. In fact, it could extend beyond spring, if an El Nino forms in the Pacific later this year.

The current odds for an El Nino - which typically means less rainfall than usual and higher temperatures across much of Australia - are about 50-50, Mr Pollock said.

Five of the bureau's eight main international models it analyses point to El Nino thresholds being crossed by the spring, and a sixth has it reached by December.

Peter Hannam is Environment Editor at The Sydney Morning Herald. He covers broad environmental issues ranging from climate change to renewable energy for Fairfax Media.