One person has died and another is missing as wildfires continue to burn across three Australian states.
In New South Wales, sudden southerly winds fanned the flames of over 100 blazes and fire officers said that a man who had chosen to stay in his property could no longer be reached.
Saturday was a "dreadful day", NSW fire chief Shane Fitzsimmons said.
Prime Minister Scott Morrison has cut short a holiday in Hawaii after being criticised for leaving amid the crisis.
Earlier acting prime minister Michael McCormack declared that more needed to be done to tackle global warming after several Australians linked the severity of this year's fires to climate change.
Since September, Australia's bushfire crisis has killed at least nine people, destroyed over 700 houses and scorched millions of hectares.
What happened on Saturday?
Increasing temperatures and strong winds worsened fires in three states.
In South Australia one individual was found dead, another was severely injured and 15 houses were destroyed about 40km (25 miles) east of the state capital of Adelaide.
In New South Wales a man was missing in the Blue Mountains west of Sydney after towns in the area were hit by an ember attack - when trimming plant is blown ahead of the main blaze and begins new fires.
However the southerly winds later eased and by Saturday evening six fires in the state were deemed to be at emergency level - the second-highest amount of danger after catastrophic - including two near Sydney.
In Canberra, a cricket game was called off because of poor air quality caused by smoke from the fires.
New South Wales leader Gladys Berejiklian urged Christmas travellers to delay their journeys.
"We are asking everybody not to travel on roads anywhere near the vicinity of an active fire if you don't absolutely have to," she said.
In Victoria, police said 142 fires had begun in the state since Friday. One of these was burning at an emergency level by Saturday afternoon.
What's driving the fires?
A combination of temperatures above 40C, low humidity and strong winds have worsened the battle for its 3,000 emergency personnel mobilised to take care of the bushfires in NSW.
"We are in a period of incredible drought and some areas have not seen rain for over 12 months", NSW Rural Fire Services Inspector Ben Shepherd told the BBC.
"These fires will likely continue to spread well past Christmas", he added.
A few of the fires in NSW were generating their own thunderstorms, the Rural Fire Service said.
Conditions were expected to improve during the next few days ahead of another period of hot weather expected next week.
"We won't get on top of these fires until we get some good rain - we've said that for months and months," Mr Fitzsimmons said.
However, weather officials say no major rainfall is expected in the next two months.
The Gospers Mountain mega-fire has destroyed about 460,000 hectares (1.14 million acres) north-west of Sydney and fire officers said there was a risk it could merge with the Grose Valley fire in the Blue Mountains.
What travel warnings are issued?
The states of NSW and South Australia are the focus of the travel warnings.
