Southern ACT residents have been warned the Orroral Valley bushfire may pose a threat to lives as the alert level was again increased to emergency level.
ACT Emergency Services Agency Commissioner Georgeina Whelan said the fire is generating its own weather pattern and had reached within two kilometres of Tharwa at 3pm.
"The fire may pose a threat to lives directly in its path," she told reporters in Canberra on Saturday.
"Driving is extremely dangerous and potentially deadly."
She said communities in the area are in danger and need to seek shelter immediately to survive.
Fire spotting is up to 10km ahead of the main fire to the southeast of the ACT border.
Temperatures in the nation's capital topped 40C for a second consecutive day with unpredictable wind changes forecast.
"The fire has created its own weather system this afternoon," the commissioner said.
"This will increase its intensity over the next few hours."
The bushfire had been downgraded to "watch and act" overnight.
The Monaro Highway has been closed after the NSW Rural Fire Service declared an emergency warning for the bushfire burning near Bredbo.
ACT Chief Minister Andrew Barr reminded Canberrans, especially in the southern Tuggeranong area, to remain vigilant.
"The fire is growing and it may become unpredictable," he told reporters.
Earlier, Mr Barr said the state of emergency in the territory is expected to remain until at least Monday.
He again urged people to stay away from the area, saying visitors are just "getting in the way".
"It is incredibly disappointing that a number of people had to be told to leave the area last night by ACT police," he said.
Emergency services were doorknocking in the ACT's western suburbs earlier in the day as a precautionary measure.
"We have a number of containment lines in place, however if they are breached the fire could continue up to the west of the ACT suburban borders," the commissioner said at a mid-morning press conference.
Wind changes could also see the whole of the ACT enveloped in smoke, similar to what happened after Christmas, from fires burning nearby in NSW.
The Orroral Valley bushfire has burned some 35,800 hectares so far, or 15 per cent of the ACT.
The Bureau of Meteorology's Dean Sgarbossa says the 40C heat along with gusty winds and dry conditions "will drive fire dangers into the severe area".
However, he told ABC news humidity will increase throughout the day, which will cap fire dangers heading into Sunday.
Saturday's forecast bushfire conditions have been compared to those in 2003, when four people died and hundreds of Canberra homes were razed.
with AAP...
