The severe fire conditions and extensive media coverage of bushfires on Tuesday would have encouraged firebugs to start more fires, experts say.
Of the 120 fires burning across the state, several were thought to be deliberately lit, including a grass fire in Shalvey in western Sydney.
Professor James Ogloff, the director of the Centre for Forensic Behavioural Science at Monash University, said severe fire days bring out ''all the thoughts and feelings that fire-setters have about setting fires''.
Fire-starting is a psychological condition in many people, yet pyromaniacs make up only a small proportion of individuals who light fires.
On an extreme fire day such as Tuesday, those who deliberately lit fires would tend not to be people looking for financial gain or revenge but rather ''typical fire-setters'' who have an obsession with fire and start fires to feel control and satisfaction, Professor Ogloff said.
''People who repeatedly set fires usually get quite a thrill from doing that,'' he said. ''They feel powerful, they feel a sense of accomplishment, they feel they've got control over something. Strangely enough, when they watch high fire days on the television and read about them, that makes them think about fire and, almost like an addiction, it's very difficult for them not to act on the impulse to set a fire.''
Of the average 52,000 bushfires a year in Australia, half are either deliberately lit or suspicious, according to research by the Australian Institute of Criminology.
Since October, the police Strike Force Tronto has charged 42 people for deliberately lighting more than 250 fires across the state.
The NSW Rural Fire Service Commissioner, Shane Fitzsimmons, said the multiple ignition points in several fires on Tuesday were indicative of firebug behaviour. ''There's no doubt we've had suspicious fire … behaviour,'' he said. ''Multiple ignition [points] can only be suspicious on a day like today.''
One deliberately lit fire came perilously close to residential areas in Shalvey on Tuesday afternoon. The five-hectare grass fire was still burning out of control at 5pm. By Tuesday afternoon, police reported they had three juveniles in custody in relation to the blaze. Local police were also on the ground in danger areas to monitor activity.
Detective Superintendent Ian McNab, a spokesman for Strike Force Tronto, said teenage boys were over-represented among firebugs and were often just bored or skylarking.
Yet Professor Ogloff said that despite Australia's long history with bushfires, programs to identify and address individuals with fire-starting tendencies were extremely underdeveloped.
He said harsher punishment - such as the maximum 14-year jail term for deliberately lighting fires in NSW - would deter some firebugs but others needed professional intervention, particularly in their teenage years. ''Most fire starters have an obsession with fire and it's very reinforcing over time. If you're feeling disaffected or lonely or unhappy, it's something that gives you a degree of satisfaction, so you will repeat it. Any teenagers who are setting fires should be seen by a professional, but we don't do nearly enough.''