Walter Lindner collapsed while working alongside his neighbor to save his heritage-listed homestead, according to ABC.
About 1,300 firefighters, including more than 120 from the neighboring state of Victoria, were tackling the blazes Sunday evening.
Firefighting forces from the Australian Capital Territory, a self-governing body surrounded by New South Wales, were also deployed to the Blue Mountains.
Forecasters are calling for hot, dry and windy conditions over the next few days, Seven Network reported.
CNN meteorologist Tom Sater said a front may slowly bring much-needed rain to some areas beginning Tuesday, but heavy winds might complicate firefighting efforts.