Destructive winds are continuing the howl across the east coast, bringing down power lines, tree branches and leaving thousands of homes without power.
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Winds up to 100km/h were recorded in South Australia late yesterday, accompanied by heavy rain, which caused widespread blackouts and felled numerous trees.
There were no reports of injuries or substantial damage but State Emergency Service volunteers were called to about 300 incidents.
The call-outs were mainly for felled trees and power lines, a SES spokesman said.
At the peak of the storm, some 10,000 houses and businesses across the state were without power and the Bureau of Meteorology (BoM) has forecast more harsh weather for later today.
"A vigorous cold front moving across southern parts of the state today is expected to produce the possibility of damaging winds, averaging 60-70km/h ... with peak gusts in excess of 90 km/h, mainly associated with showers and thunderstorms," the bureau's warning stated.
Locations to feel the brunt of the front include Adelaide, Port Lincoln, Mount Gambier, Murray Bridge, Kingscote and Naracoorte.
Scattered branches lined the streets of some Canberra suburbs after the winds ripped through early this morning.
Emergency service crews received 48 calls, with Canberra's northern suburbs the worst-affected area.
Power outages and trees on powerlines were also reported.
The ACT State Emergency Service said there were, so far, no reports of badly damaged homes.
"We haven't had any major structural damage, but it's not beyond possibility," deputy chief officer Tony Graham told AAP on Tuesday.
"It's not unusual for Canberra to get severe storm damage."
Branches are scattered across roads and footpaths, following strong winds which raged between 1am (AEST) and 5am.
Wind speeds peaked at 89km an hour shortly after 2am (AEST).
Calls to emergency services were highest from Scullin, Flynn, Kaleen and Hackett.
Power is still out in several northern suburbs.
Mr Graham said the 48 calls to emergency services was much lower tally than the average of 300 for severe storms.
Volunteer crews are expected to spend the rest of Tuesday morning cleaning up the debris, and are bracing for a return to strong winds tonight, he added.
The SES said it received more than 110 calls for assistance across Sydney after more than 7000 homes were blacked, with some outages caused by trees falling on power lines.
The wild weather, including severe wind gusts, also caused flight delays of up to an hour at Sydney Airport.
SES spokesman Phil Campbell warned residents to make sure children and pets were inside and to secure outside furniture and loose items.
"Most of the calls have come from western Sydney and we've also had calls from the Riverina, the Wollongong and Southern Highlands areas, Shellharbour, Bowral and Moss Vale," Mr Campbell said.
He said residents were dealing with trees down across roads, driveways and minor roof damage.
"We are expecting debris on the roads and urging people to park their car under cover, not under trees," Mr Campbell said.
Integral Energy said about 5000 people lost power in isolated areas of Penrith and the Blue Mountains, while Energy Australia said power had been restored to about 2000 homes in Bexley and Carlton in Sydney's south.
Sydney Airport remains open, but flights are being delayed.
"Flight schedules will be disrupted due to the high winds and delays of up to 60 minutes will be experienced on some flights," a Sydney Airport spokesman said.
"Plenty of flights have come in and out already."
In Queensland, the fire danger remains extreme as the state swelters through record-breaking temperature, but wild winds are expected to die down later today.
A total fire ban remains across the south of the state with a top of 31 degrees Celsius predicted for Brisbane city.
Brisbane is experiencing its hottest August on record, with the temperature soaring to 35.4 degrees about 4.20pm (AEST) on Monday.
Temperatures across the state have been about 10 degrees hotter than average.
Queensland Fire and Rescue Service commissioner Lee Johnson said the first real fire cycle for the year was expected during the next two days.
He said the fire ban meant no fires in the open and warned anyone using machinery, such as slashing grass, should exercise extreme caution.
Residents have been asked to immediately report any fires, including small grass fires, as they could quickly escalate.
Anyone caught lighting a fire during a fire ban faces six months in prison or a $5000 fine.