The weather bureau's rainfall maps for the past three months show virtually all the southern and eastern parts of the country have posted below or very-much-below average rainfall.

And the past fortnight of record-breaking heat across much of the continent meant fuel loads in bushfire areas were ''trumping the situation'' due to lowering moisture levels, said Jeff Kepert, the head of the high impact weather research team at the Bureau of Meteorology.

''Fire intensity is very sensitive to fuel moisture and the difference in fuels that have 1, 2, 3 per cent moisture in terms of their flammability is quite large,'' Dr Kepert said. ''It will have sucked the last bit of moisture out of the fuels over a very large area.''

Fire authorities have known for months this summer would pose large hazards, not least because the preceding two wet years had spurred vegetation growth.

The bureau's national temperature data stretches over 37,000 days. Of the 20 hottest days, seven have come this year, including the record high national average maximum of 40.33 degrees, reached on Monday.

Parts of the ''corner country'', where NSW, Queensland and South Australia meet, may have temperatures hit 49 degrees this weekend.

High temperatures, which returned to south-eastern Australia on Friday, had fire authorities scrambling to contain blazes in NSW, Victoria and South Australia, while rain in Tasmania eased conditions in that state.

While Dr Kepert stresses conditions are not at the level preceding the 1983 Ash Wednesday and 2009 Black Saturday fires, the prolonged heat spell has elevated fire dangers.

''By just crisping everything up a bit, [the heatwave] has increased the risk for the remainder of the summer,'' Dr Kepert said.

However, enhanced modelling is giving the bureau - and the authorities it informs - far greater readiness to handle the fire threat than in the past, particularly since the Ash Wednesday fires.

''The quality of our one-day forecasts back at that time is about the same as the quality of our four-day forecasts at present,'' Dr Kepert said.

''You can roughly attribute one day [of that improvement] to better computers, one day to the fact the science in the models is better and one day to the fact that the way we analyse the initial conditions for the forecast is better.

''Ultimately, this saves lives … It may not, unfortunately, save every life but the consequences are less than they would otherwise have been.''

The Bushfire Co-operative Research Centre issues its seasonal outlook each year in September, based partly on the bureau's modelling of summer weather conditions.

Richard Thornton, the centre's research director, said Australian bushfire research is now among the world's best.

''We need to maintain the intensity of our bushfire research,'' he said.

Dr Thornton said the centre had focused much of the past three years researching the 2009 Victorian fires, with limited research on future prospects, including the expected change to warmer conditions.

''We need to understand what are the things that are coming over the next decade and beyond,'' he said.