Enormous flames are no longer consuming the city of Fort McMurray, but the wildfire is still active and classified as "out of control" by the Alberta government. 

CBC News asked Alberta wildfire information officer Travis Fairweather to explain what is happening now and why officials say it will take months to extinguish the fire.   

How big is the Fort McMurray wildfire?

As of Tuesday afternoon, the Fort McMurray wildfire was 2,290 square kilometres. That's up from about 2,040 square kilometres on Monday.

Travis Fairweather

Travis Fairweather, a wildfire information officer for Alberta, says hot spots can 'sort of simmer under the surface for a few months' and then flare up again. (Wildfire Alberta)

The main reason the fire got bigger, Fairweather says, is that the main Fort McMurray fire merged with a much smaller, separate fire that had been burning to the northeast. The smaller fire, which measures roughly 250 square kilometres, actually started when embers blew off the main fire into the woods. 

Thanks to favourable weather conditions, the wildfire isn't expected to grow significantly in the coming days.

The main factors that affect wildfires are heat, dryness and wind, so "less windy the better, cooler the better, more moist the better," he says, noting that rain would be ideal, but even humidity helps firefighters. 

Where is the fire now?

The Fort McMurray wildfire has been travelling east and is about 25 to 30 kilometres from the Saskatchewan boundary, according to the Alberta government's latest update on Tuesday.    

Flames are really only visible at the front of a large active wildfire, Fairweather says. The rest is "fields of just black ash" left behind.  

That huge burnt area — including within Fort McMurray — is extremely dangerous and firefighters have months of work ahead of them, he says. They will do infrared scans from the air to find "hot spots" where smoke continues to smoulder underground. 

"Stuff like that can sort of simmer under the surface for a few months even and then flare back up when you get, you know, some hot weather and some winds again," Fairweather says. To make sure that doesn't happen, crews dig up the ground to find the smoke and extinguish the fire.  

"They're working with chainsaws and hoses and axes and shovels," he said. "It's really, really gruelling work out there for them." 

Are any more communities at risk?

The fire is "all out in the trees right now," Fairweather says. But crews are taking precautions in communities to the south, including Anzac and Gregoire Lake Estates, because "fire's very unpredictable and you never know what's going to happen with the wind." 

Crews are setting up a "dozer guard" in those areas, clearing trees so there's no fuel for the fire to burn if it arrives. The dozer guard stretches for many kilometres, he says.      

What happens if the fire crosses into Saskatchewan?

If the Fort McMurray wildfire moves into Saskatchewan, Alberta firefighters don't just pack up and hand off to their Saskatchewan counterparts, Fairweather says. 

"[The provincial boundary is] sort of an imaginary line when you think about it," he says. "We all work together."

Alberta firefighters are dealing with a similar situation on the other side of the province, after a wildfire that started in British Columbia recently spread across the Alberta boundary. 

"We have longstanding relationships with our surrounding provinces," Fairweather says. "We were helping out before it got to Alberta and now that it's on the Alberta side as well we're helping even more."

How many people are fighting the fire?

About 700 firefighters are working on the Fort McMurray wildfire. Twenty-six helicopters are being used to transport crews and to pick up and drop water and 13 air tanker planes are carrying water or fire retardant. 

There is a total of 1,547 firefighters, 121 helicopters and 28 air tankers battling 25 wildfires across Alberta right now, according to the provincial government's latest update. 

Most of those fires are classified as "under control." The Fort McMurray wildfire is the only one that remains "out of control."   

This video was made when the Fort McMurray fire was 2,040 square kilometres in size. The fire has since grown.

How does the Fort McMurray wildfire's area compare across Canada0:49

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