Fire conditions eased on some of the major fronts burning across Australia on Sunday after a cool weather change, with firefighters trying to contain blazes before the expected return of hotter conditions at the end of the week.

Prime Minister Scott Morrison visited the Rural Fire Service (RFS) headquarters in Sydney, after returning on Saturday night from a holiday in Hawaii that drew sharp criticism as the wildfire crisis in his home state deepened.

After the deaths of two firefighters Thursday night, Morrison announced he would return home early, and on Sunday he acknowledged his holiday had caused anxiety.