Fire management officer Julian Davies, left, with training officer Mick Ivill.

Fire management officer Julian Davies, left, with training officer Mick Ivill. Photo: Graham Tidy

Two summers of unprecedented rain and unusually cool temperatures have left a large fuel load of grass and unburnt forest areas in and around Canberra.

A network of 500 fire trails and strategic burns along the north-west urban edge, heavy grazing and extra grass slashing will create a fortress for the territory which forecasters say faces a higher than average risk this summer.

After a fire-fuelled tornado in January 2003 killed four Canberrans and frightened thousands more, CSIRO fire expert Phil Cheney told the subsequent inquiry the fire's penetration into urban areas under extreme conditions did not reflect a failure of fuel management on the urban interface.

An ACT Parks Conservation and Lands heavy tanker patrols a fire trail in the Uriarra Forest.

An ACT Parks Conservation and Lands heavy tanker patrols a fire trail in the Uriarra Forest. Photo: Graham Tidy

The failure was in the forest areas.

Following a 10-year strategy, ACT fire managers have created a mosaic across the landscape of different fuel levels, burning at every opportunity.

But forests have been too wet to burn this spring and the past two summers.

An ACT Parks Conservation and Lands heavy tanker patrols a fire trail in the Uriarra Forest.

An ACT Parks Conservation and Lands heavy tanker patrols a fire trail in the Uriarra Forest. Photo: Graham Tidy

Of the 12,000 hectares to be burnt this season, 200 hectares have been burnt around the urban edge in fuels dry enough to burn.

Territory and Municipal Services fire manager Neil Cooper said forests would be targeted in autumn.

''The larger burns [areas] in the forested areas are not yet dry enough to implement a successful hazard reduction fire burn.

''I'm not worried, in a lot of areas fuels have not got to that [dangerous] stage.''

Mr Cooper said it was no secret Canberra had lots of grass. ''But with grass fires, there's no fire danger until the grass dries out.''

Senior weather forecaster in Canberra Sean Carson said after only three days of temperatures over 35 degrees in the past two summers - in contrast to the long term average of 13 days of above 35 degrees - people had forgotten what a normal summer was like.

''It only takes two weeks of hot dry weather to cure the grass. I would say without doubt it is very likely that will happen.''

Bushfire Co-operative Research Centre deputy chief executive and research director Dr Richard Thornton said since the 2003 Canberra fires, weather modelling and fundamental underpinning science that impacted on fire behaviour had changed.

Much had been done to understand weather forecasting on severe fire danger days from the Canberra, Ash Wednesday and Black Saturday fires in Victoria.

Researchers looked at wind change across the country, predictors of severe blow ups, high level jets and dry slots which brought very dry upper atmospheric winds down into the fire ground which dramatically increased fire behaviour.

''There is quite a lot of underpinning science that is now used routinely across the bureau's severe weather forecasting that feeds into the fire fighters on the ground.''

After the Black Saturday bushfires, royal commission ''catastrophic'' was added to the alert ratings.

Original fire ratings were calibrated to 100, based on the worst fires seen since the 1939 fires in Victoria, but around Black Saturday fire danger ratings were peaking at 200.

''But it is more about making sure we pick the peak levels and making sure people are aware that this isn't slightly worse than a very high or severe rating, it is actually a lot, lot worse, that the houses, in the preparation you made, may not be sufficient.''

Dr Thornton could not comment on fuel loads near Canberra because he had not seen them. The CRC's website says winter frosts and snow have increased curing rates, creating above-average fire potential for the Murrumbidgee corridor through the ACT.

Dr Thornton said fuel loads were only one part of the picture, along with weather, buildings and what people did before and during a fire.

''A lot of discussion around the Canberra fires was about a prolonged drought, a lot of use of mulch in gardens because of water restrictions which helped carry fire into some of the areas around Chapman and Duffy.''

ACT Rural Fire Service chief officer Andrew Stark said green grass did not have the intensity of well-cured grass. ''When grass gets to 70 per cent [cured] it is extremely flammable and difficult to control.''

Mr Stark said a grass fire could burn four times quicker than a forest fire. But a forest fire's spotting embers could ignite flames 10 kilometres away in minutes.

Among the firefighters who backburned at Uriarra during the 2003 firestorm, Mr Cooper said the big risks remained in the mountains west of Canberra.

This spring, pioneer growth such as acacias and snarls of blackberries fill the areas burnt in 2003.

Mr Cooper said a United States Forest Service burns expert, Brian Levin, had joined the Territory and Municipal Services fire unit in August, to share technical expertise as they continued creating a mosaic of fuel control.

''We're not tied to a historical view that you cannot burn in summer.

''We will look at the weather conditions, what conditions are for the burn and following the burn and we will take it from there.''

Future burning around Googong Dam foreshore for water protection will also aim to stop bushfires from leaving the ACT and going into NSW, and another burn in the Brindabella mountains will aim to stop landscape fire from coming into the territory.

''For some of the burns, we need moisture. We will light on the ridge and it will burn back down and as soon as it comes across to higher moisture it just goes out. So that's perfect for us.''

Mr Stark said the 2003 firestorm caused interest in volunteer fire fighting to surge, before dropping away in later years. Now the territory had 487 volunteers who were skilled.