Bushfires across swathes of Australia continue to rage amid scorching temperatures and as residents in Victoria’s far east are told it’s too late to flee.

A total fire ban is in place across Victoria, while in the state’s East Gippsland region, two blazes near Ensay and Tambo Crossing have merged and emergency warnings have been issued.

In South Australia, firefighters are facing catastrophic conditions in the Adelaide Hills, through the mid-north and across to Yorke Peninsula.

Temperatures are tipped to reach the mid-40s across South Australia. Photo: ABC News/Gian De Poloni

Adelaide is forecast to reach 40 degrees and firefighters are particularly worried about the potential for breakouts in the blaze burning in the Adelaide Hills.

There are also concerns for a fire on Kangaroo Island which continues to smoulder.

A cool change in the afternoon is causing the most concern, with strong and shifting winds set to heighten the risk of bushfires spreading.

In NSW, more than 900 homes have been destroyed but that number is expected to increase with rising temperatures and dry winds forecast to peak on New Year’s Eve.

Temperatures are forecast to climb past 40 degrees in western Sydney and parts of regional NSW by Tuesday, as air pollution in the city’s southwest remains at a hazardous level.

The “mega-blaze” at Gospers Mountain, near Sydney, is expected to flare today. Photo: AAP

A watch and act alert is in place for two fires in remote parts of Western Australia, at the Stirling Range National Park and Higginsville mine site in the state’s south.

In Tasmania, residents are urged to remain on high alert as scorching temperatures combined with forecast thunderstorms and winds increase fire risk.

-AAP