A severe thunderstorm warning for parts of Victoria has now broadened to include more of the state, including metropolitan Melbourne.
The Bureau of Meteorology says it detected severe wind and rainfall near outer Melbourne suburbs Warrandyte and Eltham, and forecasts the wild weather will hit eastern suburbs and the CBD this evening.
Over the rest of the state, BOM says damaging winds and heavy rainfall could lead to flash flooding over the next several hours.
Locations likely to be affected include Seymour, Maryborough, Ballarat, Traralgon and Moe.
The state's north east and north west have been the worst-affected by the deluge so far, with a number of areas breaking their daily rainfall records.
In Sydney, heavy rain severely reduced visibility on the roads causing a spate of traffic accidents.
Some train services were disrupted and more than 30 flights were cancelled as the wild weather lashed the city.
Queensland ready for Owen
Cyclone Owen will "wreak havoc" across Queensland with remote communities braced for 280km/h winds and much of the state on flood alert, the premier says.
Annastacia Palaszczuk said the state has done all it can to be ready for Owen, which is expected to hit as a severe category four storm as early as Friday night.
The latest modelling suggests Owen will make landfall south of Kowanyama, on Cape York Peninsula's east coast, late on Friday or early on Saturday.
Other parts of Queensland could see flooding with Owen expected to dump as much as 400mm of rain on some areas in coming days.
Rain and storms are also forecast from a separate weather system in the state's southeast corner.
In central Queensland, there are concerns about possible landslides if heavy rain falls over vast tracts of land denuded by recent bushfires.
"We've just been through horrendous bushfires and now we're dealing with a ... cyclone. Owen will wreak havoc across our state and come down the east coast," the premier told the Seven network on Friday.
In a sign of how widespread the wild weather will be, 29 mayors from across the state have been involved in disaster planning meetings.
Ahead of Owen's arrival, more than 60 emergency services staff have been sent to Kowanyama and Pormpuraaw, including swift water rescue experts.
Authorities have been making sure everyone has a place to shelter, in cyclone-rated buildings. And in coastal areas likely to see wild winds, boats have been ordered back to harbour.
Owen is still a category three cyclone, with wind gusts of almost 200km/h. It could reach category four strength by early afternoon.
Dr Richard Wardle, from the Bureau of Meteorology, said communities near Owen's landfall location must be prepared for very destructive winds, heavy rain, and a significant storm tide.
Abnormally high tides could also compound any flooding on the east coast.
