© ReutersCars on Highway 3 out of Yellowknife were bumper to bumper on Wednesday as people scrambled to evacuate
Hundreds have also lined up for emergency military evacuation flights.
Local officials have given the 20,000 residents of Yellowknife, in the Northwest Territories, a deadline of noon Friday (18:00 GMT) to leave.
As of Thursday, the fire was within 16km (10 miles) of the city.
The Northwest Territories declared a state of emergency late on Tuesday as it battles nearly 240 wildfires.
"Very tough days ahead - with two days of northwest to west-northwest winds on Friday and Saturday, which would push fire towards Yellowknife," the territorial fire service said in a statement on Facebook.
There have been reports of long lines at petrol stations in the city and on the road out of town.
Resident Bill Braden told Global News he was carrying extra petrol with him after a family member told him the line at one gas station stretched a kilometre in length.
Police advised drivers to slow down as they reach Fort Providence, about 300km southwest of Yellowknife by road, as a long queue for gas was affecting traffic.
For those not staying with friends or family in other communities, the closest centre for evacuees is 1,100km south of Yellowknife.
Military evacuation flights are scheduled throughout the afternoon and evening on Thursday, with five flights to Calgary, in the neighbouring province of Alberta.
The federal transport minister has also assured evacuees that the country's largest airline, Air Canada, is capping the cost of flights out of Yellowknife.
Air Canada has added two extra flights out of the city.
Shane Thompson, environment minister for the Northwest Territories, told reporters on Wednesday that the fires had "taken another turn for the worse" and represented a "real threat" to Yellowknife, the region's capital.
"I want to stress that the city is not in immediate danger," he said. "[But] you put yourself and others at risk if you choose to stay."
Prime Minister Justin Trudeau held an emergency meeting on Thursday to discuss the wildfire situation in the northern territory.
Some residents of Yellowknife had already begun leaving earlier on Wednesday after parts of the city were put on evacuation alert, meaning they could be asked to leave at a moment's notice.
"Watching the flights sell out and the prices go up I just kind of got to a point where we should leave," Ashley Maclellan, who fled south to Edmonton with her baby, told the CBC.
Another fire is threatening the community of Hay River.
One evacuee told the CBC her car began melting as she and her family drove through embers while fleeing that town over the weekend.
Hay River Mayor Kandis Jameson pleaded with anyone remaining in the town to leave immediately.
The fire moved 30km in a few hours because of strong winds earlier this week, closing the only two highways out of the town. Then it stalled about 10km away from the town.
Resident Lisa Mundy described how her bumper had begun to melt, her windscreen had cracked and her car had filled with smoke as she and her husband left the town with their two children on Sunday.
"You couldn't see anything - we were driving through embers," she said.
About 46,000 people live in the Northwest Territories, and Canada's military has been co-ordinating the largest airlift evacuation effort in the region's history.
The communities of Fort Smith, K'atl'odeeche First Nation, Hay River, Enterprise, and Jean Marie River are all also under evacuation orders.
Kakisa, a community of about 40 people some 130km from Hay River, received an evacuation order on Thursday.
"We are all praying we get as much rain as we can," he told the BBC.
Canada is having its worst wildfire season on record, with nearly 1,100 active fires burning across the country as of Wednesday.
Experts have pointed to a warmer and drier spring than normal as the reason.
It becoming beyond 🤣 🤣 🤣 🤣 🤣 albe.