Catastrophic fire warnings are in place across the Australian state of New South Wales (NSW), where firefighters are tackling more than 100 blazes.
Authorities have urged Christmas travellers to delay their journeys as conditions threaten to intensify the bushfire crisis.
Rising temperatures and strong winds worsened fires across three states on Saturday.
Three blazes around Sydney are burning at emergency level.
“We are asking everybody not to travel on roads anywhere near the vicinity of an active fire unless you absolutely have to,” Gladys Berejiklian, premier of NSW, said at a news conference.
A combination of temperatures above 40C, low humidity and strong winds have worsened the struggle for the almost 10,000 emergency personnel mobilised to deal with the bushfires in NSW.
“We are in a period of unbelievable drought and some areas haven’t seen rain for more than 12 months”, NSW Rural Fire Services Inspector Ben Shepherd told the BBC.
“These fires are likely to continue to spread well past Christmas”, he added.
Two volunteer firefighters died on Thursday as they were tackling a large blaze near Sydney. Fires have also been ravaging the states of Victoria and South Australia, where two civilians died on Friday.
Since September, Australia’s bushfire emergency has killed eight people, destroyed more than 700 houses and scorched millions of hectares.
The states of NSW and and South Australia are the focus of the travel warnings.
In NSW, several major roads and highways have been closed, including a section of the Princes Highway.
As of 16:30 (05:12 GMT), 24 roads and highways in NSW were affected by fire, according to a government website.
Roads have been closed in South Australia as well, with residents asked to monitor the government traffic website for updates.
“If members of the public attempt to enter the areas, they will be turned away, regardless of being property owners or business owners, due to specific safety reasons,” a police official said.
