There was one surprising reason the bushfires of Ash Wednesday, 1983, were the worst in more than four decades.
It was a cold front, not the extreme heat or 10-month drought, that made the fires 40 years ago so bad.
Dry, cold winds that swept across South Australia and Victoria once fires were already burning were unusually strong and sustained.
"It was up at the highest end of the wind speed we observe, both before the [cool] change and even more particularly in central Victoria after the change," Graham Mills, an affiliate at Monash University's School of Earth, Atmosphere and Environment, told the ABC.
Dr Mills studied the weather conditions on Ash Wednesday and found that such patterns could be the difference between a bad fire day and a disastrous one.
In the Ash Wednesday fires, the arrival of a cool change in the late afternoon led to sudden swings in fire direction and huge expansions in the size and intensity of the fires.
Firefighters describe the various blazes as "exploding" at that moment, sweeping across crews that were trying to contain the flanks of fires and leading to a number of deaths in South Australia and Victoria, when fire fronts shifted direction.
"They were a kilometre across, [then] you suddenly had a fire from 20km across and winds were also extremely strong," Dr Mills said.
"[With] some changes, you don't get such strong winds after the change."
Change in cold front research focus
Prior to Ash Wednesday, Dr Mills said cold front research had focused on rainy events in the cooler months.
But the bushfire disaster helped reveal the significance of cool changes to fire behaviour, leading to safer firefighting practices and better provision of information to emergency services.
"It alerted people to the fact that this behaviour could both be understood, could happen and could be predicted," Dr Mills said.
"So instead of saying, 'It's going to be a bad fire day and it's going to be a cool change', the fire agencies could say we'll get forecasts saying, 'What is the wind going to be at this point, at every hour through the day?'
"That sort of thing is just crucial for saving firefighters' lives."
Thanks to advances in monitoring and modelling, these potentially disastrous weather systems can now be forecast up to a week out, giving emergency services time to prepare and residents time to plan.
More and better information available
Bureau of Meteorology fire weather forecaster Mika Peace said there was also far more information available to meteorologists and emergency services on bad fire days.
"I think one of the biggest things that changed from Ash Wednesday to now is the communication and the way that we've now got technology to do real-time communication on what's going on," she said.
"One of the biggest things is probably not necessarily on our side in terms of weather forecasting, but with the Country Fire Service, just how quickly they can get to ignitions these days [for example, with firefighting aircraft].
"So, effectively, with the fire agencies, they work on about 20 minutes — if they can get to a new ignition within about 20 minutes, then they can put it out, but that's using today's technology in terms of communications, and all the other information that's available."
But even with all the advancements and understanding, Dr Peace said managing bushfires was getting harder, thanks to climate change.
"Things aren't going to get better and there's a lot of concern about what the scenario looks like in the future with dry vegetations, and cycles of dry and wet," she said.
"Going from La Niña now where everything's really green and all the vegetation's growing, to then we're going to go into a dry cycle as well, so that fuel in the landscape is going to be available to burn.
"As we go into the next phase of dry years, the fire risk increases phenomenally."
