The entire population of Fort McMurray — 80,000 people who have fled a raging wildfire — now face a long wait before they can return to their homes and resume anything close to normal lives.

That was the grim news delivered Thursday evening by Alberta Premier Rachel Notley, who warned residents it will take many days before their city is safe to live in again.

Notley refused to speculate about how long the wait might be.

"Unfortunately, we do know that it won't be a matter of days," she said.

May 5 - 10:50 p.m. A brief message from Darby Allen <a href="https://twitter.com/hashtag/ymmfire?src=hash">#ymmfire</a> <a href="https://t.co/0hb9TkoYwH">pic.twitter.com/0hb9TkoYwH</a> —@RMWoodBuffalo

With thousands of people now staying in evacuation centres, or with friends or relatives, the government is working on a plan to find "transitional housing" for families who lost everything when the wildfire swept away entire streets.

On Thursday, about 4,000 evacuees stranded north of Fort McMurray were flown to Calgary or Edmonton from runways at two oilsands camps, where many have been staying.

Wildfire Update – May 5, 9:20 p.m. <a href="https://twitter.com/hashtag/ymmfire?src=hash">#ymmfire</a> <a href="https://t.co/K59ZlElo0v">pic.twitter.com/K59ZlElo0v</a> —@RMWoodBuffalo

On Friday morning, other residents are expected to be allowed to drive in RCMP-led convoys down Highway 63 and straight through their city, past the ruins of neighbourhoods where more than 1,600 homes and buildings have burned.

Once safely south of the city, the cars and trucks will head south toward evacuation centres or other accommodations.

Fire officials do not yet know what started this massive wildfire, but said Thursday they now know the only force powerful enough to stop it will be a significant change in the weather.

'We still have a long way to go'

Supercharged by winds, the wildfire ballooned from 10,000 hectares on Wednesday evening to about 85,000 hectares by dawn Thursday.

By day's end Thursday, the fire's progress had slowed significantly, and officials continued to estimate its size at 85,000 hectares.

Michael McWilliams captured footage of the wildfire closing in on May 5 4:06

"We're not out of the woods yet," said senior wildfire manager Chad Morrison. "We still have a long way to go."

The main body of the fire, now south of the city, is expected to continue to burn out of control, perhaps for many days to come.

More than 100 firefighters and 10 helicopters and 16 air tankers continue to fight the wildfire, with more resources on the way.

In addition to the firefighters battling the blaze, more than 200 firefighters and 25 fire trucks are in the city itself, protecting homes and buildings.

But Morrison cautioned that all of that effort and equipment cannot stop the inferno.

"Let me be clear, air tankers are not going to stop this fire," Morrison said earlier in the day. "This is an extreme fire event. It's going to continue to push through these dry conditions until we actually get some significant rain to help us.

Ellyse Naughton, left, holds her toy robotic dog as her mother Erin looks at her phone as they camp at the Christina Lake campground in Conklin, Alta., on Thursday. People are being urged to stay out of Fort McMurray as crews continue to fight fires. (Mark Blinch/Reuters )

"I expect this fire to continue to grow over the next number of days."

Thursday was much cooler than previous days, with a high of about 17 C, but winds continued to blow out the northwest, at times up to 40 km/h.

'Extreme threat' in Anzac and Gregoire Lake Estates

"We expect the fire to continue to grow in the southeast corner," Morrison said, "but it will be going away from the community."

"It's been brutal." Marisa Heath has been at the North <a href="https://twitter.com/hashtag/FortMacFire?src=hash">#FortMacFire</a> roadblock since 8 pm Wed. <a href="https://t.co/izyDlukhdl">pic.twitter.com/izyDlukhdl</a> —@warnicam

At 5:15 p.m. MT, the Regional Municipality of Wood Buffalo reported that the communities of Anzac and Gregoire Lake Estates, south of the city, were under "extreme threat" from walls of flames.

Fire crews on the ground expect to receive reinforcements soon from other parts of Canada. Ontario is sending 100 firefighters and Quebec has dispatched four air tankers.

The fire, which covers more than 850 square kilometres (an area the size of Calgary), is so big it has created its own weather, with reports of lightning coming from the billowing clouds of smoke, Morrison said earlier in the day.

Though it is huge and still growing, the Fort McMurray fire is, so far, nowhere near the largest wildfire ever ignited in Alberta. That distinction belongs to the Richardson Backcountry Fire, which burned more than 700,000 hectares of boreal forest northwest of Fort McMurray in 2011.

But in the end, that fire, though it burned for months, took not a single home or building.

Rachel Notley on what's going on in Fort McMurray and aid efforts 0:30