(Adds forecast for overnight, Sunday)
SYDNEY, Feb 7 (Reuters) - Aircraft dropped water bombs on raging Australian bush fires and homes went up in flames on Saturday as a once-in-a-century heatwave sent temperatures in Melbourne to their highest on record.
Wildfires are a natural annual event in Australia, but this year conditions are some of the worst in living memory: a combination of scorching weather, drought and tinder-dry bush.
Local media have called it a "once-in-a-century heatwave".
On Saturday temperatures in Melbourne soared to 46.4 degrees Celsius (115.5 Fahrenheit), the highest on record, local media said, with the mercury in the community of Laverton on the city’s west hitting 47.9 C (118.2 F).
Officials said dozens of fires were blazing across the country’s densely populated southeast, and police said at least one that hit Sydney’s metropolitan area late on Friday had been deliberately lit.
A major fire in parkland east of Melbourne had burned more than 160 hectares after jumping containment lines overnight, and despite water bombs dropped from aircraft proved hard to control as winds fanned the blaze. Entire trees went up in flames, and roads were closed.
As evening fell, firefighters were preparing to stay on the job overnight for the second night running. One firefighter suffered serious burns, ambulance officials said.
As flames erupted around one property under threat from the fire, owner Graham Kinross and his wife stayed and watered down their home and land, as the area was swallowed by thick, choking orange and grey smoke.
"We would always stay and defend," a visibly shaken Di Kinross told local media, after flames appeared to wipe out parts of their neighbour’s property.
Victoria state’s Country Fire Authority told Reuters it had received reports of houses burnt in parts of the state, but still had little detail.
"It is extremely dry. We do have some concern about the winds picking up and having an impact on the fire," a spokesman told Reuters.
An "urgent threat message" was posted for local communities to be prepared to be hit by fire and threat notices were issued for several other areas. Fire bans were in force in three states, and in South Australia a fire broke out just north of Adelaide.
STAY AND FIGHT
Fire officials in Australia have advised residents to stay and defend their homes against bushfires, as most homes are damaged not by the actual firefront but burning embers blown onto roofs.
Evacuation is a last resort and fire officials advise residents to leave well before a firefront nears. More than 80 residents of two nursing homes were evacuated as the fire east of Melbourne spread on Saturday, and the fire front stretched for kilometres.
In New South Wales, authorities said more than 40 fires were burning, with bushfire emergencies declared in several places. Smoke covered many areas of Sydney, which came under threat from two fires late on Friday.
Fire bans were in force in three states and were expected to be reissued for Sunday, also forecast to be a day of high fire risk.
Fire fighters were preparing to stay out overnight to combat a large fire north of Sydney.
Bushfire researcher David Bruce said it was too early to assess the full impact of the fires.
"The weather is as bad as it’s ever been. A change is going to come through later and not necessarily for the better for some of these fires," said Bruce, of the Bushfire Cooperative Research Centre.
The heatwave will not affect commodity crops such as wheat and sugar, which are grown predominately in western and northern Australia.
Police blamed a fire that broke out in the inner-Sydney district of Lane Cove on Friday night on arson. The fire burnt several hectares of a national park within the Sydney metropolitan area, threatening nearby homes.
Researchers say around half of the bushfires in Australia are deliberately lit.
The heatwave has caused a spate of heat-related deaths, which has left morgues struggling to cope, while transport and power services have repeatedly broken down in the hot weather. A series of breakdowns was reported in and around Melbourne on Saturday.
Tens of thousands of firefighters are on standby to cope with bushfire outbreaks in three states, while authorities in Victoria warned in advance that Saturday’s conditions could be worse than those that led to the deadly "Ash Wednesday" fires of 1983, which killed 75.
Forecasts for Sunday were for slightly cooler weather, with temperatures generally in the 30s Celsius, although the fire risk remains high.
(Sydney Newsroom +612 6273 2730)