THE NSW Rural Fire Service fears ground they made fighting fires could be lost with temperatures set to soar as conditions worsen across the state this weekend.
A cooler Thursday gave firefighters an opportunity to get on top of 120 fires, 17 of which remain out of control.
But while the warning system was downgraded for most parts of the state, in particular those in the ''catastrophic'' range seen on Tuesday, it may only be temporary relief.
The Bureau of Meteorology forecasts a return to heatwave conditions that will make Friday a furnace for most parts of the state.
In Bourke the bureau expects a maximum of 47 degrees on Saturday and Sunday, while Dubbo residents are facing temperatures of 44 to 45 degrees. The Hunter region is also bracing for extreme temperatures.
NSW RFS Commissioner Shane Fitzsimmons said a statewide total fire ban would be in place on Friday in response to the rising temperatures.
''It's going to be awful. It's going to be difficult for firefighters and the communities affected,'' Mr Fitzsimmons said.
Fire incidents map. Zoom in to see current incidents. Courtesy unorthodox.com.au.
''The only consolation we have is that winds are going to be slightly less than they were on Tuesday. But we can't ignore the widespread existence of fires already active across the state.
More than 100 fires are scattered over NSW, with the most significant areas of concern about 12 kilometres west of Sussex Inlet, south of Nowra. More than 130 firefighters are still working to contain the fire that has burnt through 5840 hectares.
A fire burning 20 kilometres east of Cooma is not yet under control after burning through 9400 hectares. This morning, the NSW RFS upgraded the blaze to a ‘Watch and Act’ status, warning properties in the Kybeyan Valley may come under threat later today.
Another fire burning in rugged country about 11 kilometres west of Yass is still a threat as it is not fully under control.
Mr Fitzsimmons said nearly 2000 firefighters were on the frontline while ''thousands'' were on standby to be deployed if their area became affected.
Victoria is also bracing for severe fire conditions on Friday, with a statewide total fire ban declared and authorities keeping a close eye on two blazes.
Temperatures of 42 degrees are expected in some areas and north-westerly winds of up to 50km/h are forecast.
Two districts - the Wimmera and north-central - will have extreme fire danger. There are 12 fires in Victoria, with two of concern to authorities, Fire Services Commissioner Craig Lapsley said.
Despite dire warnings and fears NSW's ''catastrophic'' conditions would cause widespread destruction, so far only one house has been lost, at Yarrabin in the Cooma-Monaro region.
The RFS said about 370,000 hectares had been burnt and an estimated 10,000 sheep worth $1 million have died.
Meanwhile, Blue Mountains police are appealing for help as they investigate three suspicious grass fires they believe were deliberately lit. The fires were quickly extinguished by the RFS on Wednesday.