The fires were the worst we've had in living memory.
Depends on what you mean and on when you were born, I guess.
Of all the recorded fires in Australia, the 2009 Black Saturday bushfires in the state of Victoria claimed the largest number of recorded deaths of any individual Australian bushfire or bushfires season – 173 fatalities over 21 days. The largest known area burnt was between 100–117 million hectares (250–290 million acres), impacting approximately 15 per cent of Australia's physical land mass, during the 1974-75 Australian bushfire season. The most number of homes destroyed was approximately 3,700 dwellings, attributed to Victoria's 1939 Black Friday bushfires.
In 2019/20: 18,626,000 ha (46,030,000 acres) were destroyed, which makes it the 5th worst fire according to that standard.
1974/75: 117,000,000 ha (290,000,000 acres)
1969/70: 45,000,000 ha (110,000,000 acres)
1968/1969: 40,000,000 ha (99,000,000 acres)
2001/2002: 38,000,000 ha (94,000,000 acres)