Australia fires: Crews brace for dangerous heatwave

A heatwave forecast to sweep across Australia in coming days could escalate conditions for the nation's bushfires, authorities fear.

Temperatures are set to hit over 40C (104F) from Friday in several bushfire-affected states including New South Wales, South Australia and Victoria.

There are more than 100 fires burning, with the largest to the west of Sydney.

Firefighters took advantage of cooler temperatures over Christmas to try and and contain fire fronts.

"[It] is all about shoring up protection before we see the conditions deteriorate again," said New South Wales Rural Fire Service Commissioner Shane Fitzsimmons on Friday.