MELBOURNE (REUTERS) - Australian firefighters used cooler conditions on Christmas Day to try and contain bush fires ahead of hot, dry weather later in the week, as leaders and communities thanked them for sacrificing time with their families over the holidays.

In the state of New South Wales (NSW), which saw entire towns devastated by fires over the weekend, state premier Gladys Berejiklian and the head of the NSW rural fire service, Mr Shane Fitzsimmons, attended a breakfast organised by volunteers in the small town of Colo, 90km north-west of Sydney.

"Community volunteers provided food, company, conversation, wrapped presents & hampers to share for crews heading into the field," Mr Fitzsimmons tweeted. "It was just lovely & spirits were high."

Christmas Day offered cooler conditions in many parts of the country as firefighters, many of them volunteers, spent the day trying to contain blazes.

Intense heat is forecast to return again by the weekend, especially in Australia's south, where temperatures are expected to exceed 40 deg C.

The last few months have seen more than 900 homes lost across the dry continent, according to authorities, even though the southern hemisphere summer has not yet reached its mid-point.

The fires have destroyed more than 3.7 million hectares across five states and at least six people have died in NSW and two in South Australia during the bush fire emergency.

Prime Minister Scott Morrison used a Christmas message to thank volunteers for their willingness to spend the day away from their families.

"As we look forward to next year and as we celebrate this Christmas I want to thank all of those who serve our nation,"Mr Morrison said in a video shared on social media on Wednesday morning.

Mr Morrison has faced sustained political pressure as the bush fires have raged, following his decision to take a family holiday to Hawaii last week and his conservative Liberal-National coalition government's climate policies.