Hundreds of firefighters were battling blazes in four states with homes threatened in New South Wales and the island state of Tasmanaia, where officers said they were facing "near-record fire danger."

In Tasmania, where the mercury hit 33.1 deg C (91.6 deg F), billowing smoke threw traffic into chaos, while 11 of 18 fires across the state were still out of control.

"I have never experienced weather like this at this time of year," Tasmania Fire Service spokesman Danny Reid said amid unconfirmed reports that flames had already engulfed one house.

"Right across the state we've got 18 fires, and out of those 11 are not yet contained but their is only the one in (Hobart's) eastern suburbs that is causing us any concern," he told the Australian Associated Press.

Unseasonably high temperatures for October, the country's worst ever drought and suspected cases of arson sparked devastating fires, destroying hundreds of hectares of bush and threatening property.

Worst affected in terms of the number of fires was the state of Victoria, where temperatures as high as 36.5 deg C (97.7 deg F) sparked as many 260 fires as the annual fire season hit about two months early

In New South Wales, dozens of homes in the north of the state's Hunter Valley wine growing region were threatened, and remote bushland burned in Sydney's far south-west.

Temperatures in the high 30s on Wednesday saw 38 fires break out across the state of South Australia, most of which were under control by Thursday.

However, high winds hampered efforts to fight the blazes in Victoria, where firefighters struggled to stand in gusts that reached 50 kilometres (31 miles) per hour.

While police put a number of the fires down to arson, the Australian Green Party blamed global warming for the volatile conditions.