Wind gusts of above 100 kph battered southeast Australia while temperatures over 40 degrees Celsius made firefighters' task extremely difficult, reports Xinhua news agency.
So far this bushfire season, an estimated 1,000 homes as well as nine lives have been lost, including those of two volunteer firefighters.
"Elevated fire danger is being driven by exceptional heat and strong, even damaging winds making their way from the interior of the country," Bureau of Meteorology scientist Jonathan How explained.
Around 30,000 people in Victoria state's East Gippsland region were asked to evacuate as out of control fires threatened communities.
Popular with hikers, campers and families, especially during the Christmas holiday season, the area in Gippsland Valley affected by bushfires is over 15,000 square km.
A cool change predicted for Monday afternoon threatened to make the situation even worse, bringing gustier winds and the chance of thunderstorms.
"This will continue to create dangerous conditions for the fires beyond today, so with hazardous weather set to impact the southeast during this busy holiday period, it's vital to keep yourself and loved ones safe," How said.
Overnight, a fire in eastern Victoria emitted a 14-km-high pyrocumulonimbus cloud which resulted in lightning strikes.
The possibility of "dry thunderstorms" was also worrying officials in the State of South Australia (SA), where lightning strikes had already started several fires.
The mix of heat, wind and thunderstorms created catastrophic conditions for SA firefighters, with fires ravaging the popular wildlife sanctuary of Kangaroo Island, as well as the hills west of State capital, Adelaide.
In Western Australia, a giant fire in the goldfields region has burnt through 148,000 hectares since it began on December 16, posing a risk to lives and property, while another fire which started on Boxing Day took around 200 firefighters to keep it contained.
Meanwhile, in the state of New South Wales, fires continued to rage west of Sydney and once again covered the city in dense smoke.
Canberra has cancelled it's New Year's Eve fireworks due to risk of fire and some members of the public called on Sydney to do the same.
However, organisers said that the iconic celebration, centering on the Harbour Bridge, will go ahead as planned.
( With inputs from IANS )