In what may be a prelude to a long, fiery summer ahead, dozens of firefighters backed by 20 trucks and two water-bombing helicopters battled to contain a blaze in Forestville Park in Tony Abbott's electorate of Warringah. Abbott's house is barely a mile away.

Josh Sheedy, a 24-year-old volunteer with the Rural Fire Service, was watching horse racing on TV with friends in nearby Belrose, when called into action.

"The flames were crowning across the trees," Sheedy said. For 12 hours, Sheedy worked to contain the 20-hectare fire in bushland from burning closer than 30 metres from homes.

"Three sides of the fire were surrounded by houses," said Peter Bull, 39, another Belrose RFS volunteer, who was diverted from hazard reduction burns at nearby Ingleside to the Forestville blaze.

"It was a hot and reasonably windy afternoon," Bull said, adding that the quick response to the fire ensured "at no stage was it threatening the homes".

The absence of property damage and the political distractions of the day meant media focus remained elsewhere. (Abbott, a low-key but enthusiastic RFS volunteer in the district, might have changed that had he swapped his blue tie and suit for fluorescent overalls after voting.)

Fire emergencies

Not so three days later, though, when the mercury again climbed past 30 degrees - Saturday and Tuesday marked the earliest Sydney has seen such heat in spring - and the winds whipped up.

By Tuesday afternoon, the media was swarming to capture images and stories as blazes erupted in forests and grassland to Sydney's west and north, destroying a handful of properties and threatening many more.

Officials had come close to declaring Tuesday a total fire ban day. "You've got really a summer's day happening 10 days into spring," Deputy RFS Fire Commissioner Rob Rogers said.

The RFS issued four emergency warnings as the fires sent plumes of smoke over the Sydney basin. Authorities mobilised 14 aircraft and more than 1200 fire fighters, including Bull, who halted his work as a site manager to jump on one of six RFS trucks carrying 36 crew from the Warringah and Pittwater district. Bull worked on the Marsden Park fire which authorities said on Friday was likely caused by arson.

Aaron Coutts-Smith, a senior climatologist at the Bureau of Meteorology, said the relative absence of cold fronts since the first half of June has produced unusually hot and dry conditions. The bureau's forest fuel dryness factor index has the region stretching from Gosford to Sydney's north down to south of Wollongong at its second highest rating.

And no wonder. Sydney remains on course for its hottest year in 150 years of data after the mildest winter on record.

Rainfall in July and last month was barely a quarter of the average.

"We've had now seven weeks without meaningful rain, and we've got a lot of grassland out there on the back of three really wet years," Rogers said. ''When you put all that together, we're quite concerned."

Record start to spring

The first 12 days of the month have easily been the hottest start to spring with average maximums of 24.9 degrees, nearly five above the norm. The next warmest such period, at 23.15 degrees, was set way back in 1895, Dr Coutts-Smith said.

Minimums are also running at 14.2 degrees, 0.8 degrees above the previous record set in 1988, and 3.1 degrees above average.

Thursday also marked the 20th consecutive day of at least 20 degrees, beating the previous string of such days so early in the season set in 2001. The sequencing of the weather - a burst of rain before a long warm spell - also tends to set up vegetation for fire.

While Friday's cooler conditions may usher in the city's first rains for a month, the 2013-14 season is likely to at least match last year's intensity, itself the most active fire season in NSW for at least a decade.

Excluding the state's far west and north coast, most of NSW - along with the ACT and western Victoria - can expect above average fire activity this year, according to the seasonal fire outlook issued earlier this month by the Bushfire Co-operative Research Centre.

Severe events

Stuart Ellis, chief executive of the Australasian Fire and Emergency Service Authorities Council (AFAC), the peak industry body, said fire activity has generally been on the rise. "We've certainly had an increase in severe events experienced over the past 10 years," he said. "Fires have tended to be more, larger and of greater severity."

While the public's memory may have been seared by conflagrations such as the 2009 Black Saturday fires in Victoria, the 2003 Canberra fires or last summer's blazes in southern Tasmania, the incidence of dangerous fire weather has in fact increased significantly across many Australian locations since the 1970s, the Bureau of Meteorology says.

In its submission to a Senate inquiry earlier this year into extreme weather, the bureau noted climate change is likely to heighten the risks of catastrophic fires. It's advice that Abbott, famously lukewarm about the science of climate change, will have to weigh up even as his new cabinet makes scrapping such bodies as the Climate Change Authority and the Climate Commission a priority.

"Projected rising temperatures and likely decreases in winter and spring rainfall across southern Australia will contribute to the bushfire threat," the bureau said.

"In addition, climate modelling shows the potential for an increase in the frequency of the summer-time weather systems that are associated with the most extreme and damaging bushfire activity in south-eastern Australia."

Longer fire season

So far, though, research published last year examining the changes in fire weather between 1973 and 2010 found summer to be showing the weakest seasonal trend.

Instead, the study, by researchers Hamish Clarke, Chris Lucas and Peter Smith, identified a trend that gives experts at least as much worry: a lengthening fire season.

"The fire season's going to start earlier and last longer, and that's going to have major implications for prescribed burning," said Andrew Sullivan, team leader of CSIRO's bushfire dynamics group.

Prescribed burning - also known as hazard reduction blazes - is the main weapon in the arsenal of authorities trying to reduce threats. In NSW this season, many of the RFS's 70,000 volunteers, including Bull and Sheedy, have been racing to make the most of the favourable conditions to reduce fuel loads. Given members' day jobs, most burns are weekend affairs.

Such burns, though, carry their own risks. Fire investigators are examining to see how many of this week's fires may have been controlled burns that escaped or re-ignited, including the election-day blaze at Forestville.

AFAC's Ellis said the risks are usually warranted: "It is very evident that burning at the time of our choosing even with the risks involved is far preferable to having to try to put out a fire with a large amount of accumulated fuel."

Drying out

A paper co-authored by Sullivan last year on climate change and fire behaviour in eucalypt forests, took observations from 1961 to 2010 for a western Sydney region - an area that saw several fires this week - and used a climate model to project forward to the century's end.

"The frequency of the warm, dry years essentially doubles," Sullivan said. "The frequency of the cool wet years reduces by about a third."

The windows for prescribed burning will likely narrow, particularly in spring, as moist winter conditions limit when such burning can start. The early onset of hot conditions will also curb how long such activity can be safely carried out. Less load reduction means fires will be harder to stop.

"The initial attack on new fire outbreaks is most influenced by the condition of the fuel," Sullivan said. An area where prescribed burning has been carried out is "much more easily put out".

Jo Watson, who lives near Abbott in Forestville and was visiting a park near the weekend blaze, said she would like to see more controlled burning in her suburb, one of many in Sydney where houses nestle close to bushland.

Watson, whose block backs onto the Garigal National Park about 20 kilometres from downtown Sydney, says residents want some of the build-up in fuel reduced.

Still, Watson said she holds no strong fear of fires. Her father, a long-time RFS volunteer, has already has been active in extinguishing fires further up the coast. "It's part of living here," she said.