Emergency crews have tackled several fires in the territory and across the border since conditions deteriorated on Monday, while one man has been flown to Concord hospital in Sydney with serious burns.

ACT Emergency Services Agency Commissioner Dominic Lane said the continuing heatwave meant a total fire ban would stay in place across the Canberra region on Friday.

''This weather is not going away,'' he said. ''We're going to continue to see, for quite some days yet, elevated temperatures.

''Looks like it could be record breaking here in Canberra, in a number of ways.''

Firefighters brought under control on Thursday afternoon a three-hectare blaze near the Kings Highway on the border of the ACT and NSW.

At the fire's peak, 37 firefighters, 13 fire trucks, two commanders and two helicopters were on the scene.

The fire was first reported at 2.15pm, with ACT and NSW Rural Fire Service members at the scene throughout the afternoon. The cause of the fire is under investigation.

Earlier, a blaze in Molonglo left a homeless man with serious burns.

ACT Fire and Rescue was called to the one-hectare fire at 5am.

Witnesses said they saw a man trying to start a fire in the area earlier. Officers soon found the 48-year-old, who was flown to Concord hospital with serious burns to his throat, chest and arms.

The man will be helping police with their inquiries.

Acting Chief Police Officer David Pryce declined to comment while the investigation was continuing, but it has been confirmed that police will speak to the man about the two suspicious fires extinguished in the area on Wednesday and Thursday.

Officer Pryce said anyone caught lighting a fire during the total fire ban would face serious consequences, including potential jail time.

''You could face charges of arson or other more serious crimes ranging from 15 years to 20, 25, and even life in the case where someone may lose their life as a result of your actions,'' he said. ''Arson or any fire offence at the moment, while we're facing a total fire ban in the ACT, poses a serious risk to the public.''

His comments followed criticism from Rural Fire Service members in NSW regarding the lack of preparation by residents across the Queanbeyan and Cooma regions.

Fred Nichols, from the Cooma Rural Fire Service, said significant fuel loads remained across the region and people needed to be wary of using equipment such as slashers or mowers over the coming days.

''It doesn't take long for a spark to get out into the bush,'' he said, ''especially between Cooma and Canberra. It would take the tiniest little fire to get things going.''

Crews continuing to tackle blazes near Yass and the Kybeyan Valley near Cooma have also been warned about possible lightning strikes as a weather change comes through on Friday night.

Meanwhile, three blazes were also burning near Jindabyne.