Melbourne and Adelaide battered by southern Australia storms
Melbourne and Adelaide are recovering from severe electrical storms that swept across southern Australia overnight.
Torrential rain and lightning caused morning commuter chaos in Melbourne.
Power surges disrupted train services while rain flooded roads and trapped some people in their cars.
Sydney, which is sweltering in temperatures above 30C (86F), could be hit by the same weather system this evening, forecasters warn.
Melbourne authorities said most of the city's trains would resume operating for the evening peak commuter period, after a power surge caused by a lightning strike disrupted signals at Flinders Street Station, the city's major commuter hub.
A lightning strike also reportedly sparked a fire that destroyed a house in south-east Melbourne.
Metro Trains Chief Executive Officer Andrew Lezala said lightning had hit a number of installations overnight, creating damaging power surges.
"Pretty much all services were disrupted," Mr Lezala said at a press conference. "The network is coming back and we expect to run a full service for the evening peak," he said.
The city received its highest 24-hour rainfall since September last year, with 25.6mm (one inch) falling by 09:00.
In South Australia, a spectacular thunderstorm overnight generated about 80,000 lighting strikes in 24 hours.
Bureau of Meteorology senior forecaster Vince Rowlands said lightning had started fires in the state's north.
The bureau's Duty Forecaster Sarwan Dey told the BBC the intense weather across Victoria and South Australia was caused by a trough of low pressure that began several days ago in Western Australia.
Although it weakened as it travelled east it mixed with moist air to create the spectacular lightning display in South Australia, he said.
"The conditions were right for that kind of lightning storm to happen," said Mr Dey.
Temperatures are expected to hit 31C in Sydney and as high as 37C in western New South Wales (NSW). There is a total fire ban in north eastern NSW.
"The weather system in Victoria will move across and reach central NSW, this evening," said Mr Dey.