In the first week of December 1979, a heatwave combined with dry conditions caused the outbreak of bushfires in New South Wales, in the Sydney region. Numerous fire incidents were reported in the following weeks, in Duffys Forest, Lucas Heights, Terry Hills, Ingleside, Belrose, Elanora Heights, Lithgow, Mount Wilson, Mount Tomah and Grose Valley.

The fires caused widespread damage to millions of hectares of land. Critical infrastructure was damaged or destroyed, including communication equipment, roads, property fencing and railways. Twenty-eight homes were destroyed and a further 20 homes damaged.

The deaths of five firefighters were attributed to the fires.

By the end of December the fires were under control. More than a million hectares of land were burnt at a cost of $10 million. A number of the reported fires were deliberately lit by arsonists. 

At the time of the fires, the state was experiencing its driest period since 1972.