(Recasts)
By Alison Bevege
SYDNEY, March 18 (Reuters) - Bush and grass fires sweeping across Australia's southeast destroyed homes, killed cattle and forced hundreds to flee on Sunday as dry, hot winds fanned the flames.
No deaths or serious injuries were reported as of Sunday afternoon.
The fires, believed to have been sparked by lightning on Saturday, were raging out of control across the state of Victoria's rural southwest.
"We've been watching the weather now for a while. We've been 30 or 40 days without rain, so we knew we had a dry landscape ... we were ready in Victoria for what was a hot, dry and windy event," said Emergency Management Commissioner Craig Lapsley.
About 280 firefighters were battling the blazes while 22,000 homes were without power after the high winds brought down trees, Lapsley said. About a dozen homes were destroyed.
In the northern city of Darwin, about 25,000 homes were also without power after a tropical cyclone felled trees. No deaths were reported. roads in Victoria were closed on Sunday with residents told to stay in their homes as it was too dangerous to risk being caught by the flames in the open or to navigate the roads in the thick smoke.
The winds were expected to ease on Sunday evening, Bureau of Meteorology Victoria senior forecaster Peter Newham told Reuters.
The bureau issued fire weather warnings for Victoria, the Australian Capital Territory and the eastern state of New South Wales which sweltered in temperatures of up to 41 C (105.8 F) on Sunday.
Bushfires are a common and deadly threat in Australia's hot, dry summers, fuelled by highly flammable eucalyptus.
In January, hundreds of holidaymakers had to be rescued in a boat evacuation from the beaches of the Royal National Park south of Sydney, when they became trapped by bushfires. 2009 Black Saturday bushfires in Victoria killed 173 people and injured more than 400.
( Editing by Nick Macfie)