The Canadian city ravaged by a massive wildfire has been reprieved after cold temperatures and light rain stabilised the blaze, officials said.

Fire Chief Darby Allen said 85% of Fort McMurray remains intact, including the city centre, and Alberta's premier Rachel Notley said officials hope to provide a schedule within two weeks for thousands of evacuated residents to return home.

Ms Notley said about 2,400 homes and buildings were destroyed in Canada's main oil sands city, but firefighters managed to save 25,000 others, including the hospital, municipal buildings and every functioning school.

"This city was surrounded by an ocean of fire only a few days ago but Fort McMurray and the surrounding communities have been saved and they will be rebuilt," she said.

Ms Notley got her first direct look at the devastation in Fort McMurray on Monday after cold temperatures and light rain stabilised the massive wildfire to a point where officials could begin planning to get thousands of evacuated residents back.

The break in the weather left officials optimistic they have reached a turning point on getting a handle on the massive wildfire. The temperature dipped to 7C on Monday after a week where the region had unseasonably warm temperatures.

Ms Notley flew in on Monday morning to meet local officials and took a ground tour of the town before holding a news conference at the emergency centre.

"I was very much struck by the devastation of the fire. It was really quite overwhelming in some spots," she said. "But I will also say that I was struck by the proximity of that devastation to neighbourhoods that were untouched."

More than 40 journalists were allowed into Fort McMurray on a bus escorted by police. The forest surrounding the road into town was still smouldering and there were abandoned cars.

The Beacon Hill neighbourhood was a scene of utter devastation with homes burned down to their foundations.

Mr Allen said of the fire: "This was a beast. It was an animal. It was a fire like I've never seen in my life."

In the early stages of the blaze he feared that as much as half the city could burn down

"I just want to let the people know that we're in pretty good shape," he said. "Typical of the damaged areas you'll see structures that are completely gone and structures that are intact."

Mr Allen said at one point the fire raced down a hill to the corner of a bank, but firefighters were able to halt the encroaching flames at the bank. Had they failed to stop it there, the fire would have destroyed the central business district, he said.

More than 88,000 people have left Fort McMurray since the fire broke out last Tuesday in the heart of Canada's oil sands region. The bulk of the city's evacuees moved south after Tuesday's mandatory evacuation order, but 25,000 moved north and were housed in camps normally used for oil sands workers until they also could be evacuated south.

Gas has been turned off, the power grid is damaged and water is undrinkable in Fort McMurray. More than 250 power company workers are trying to restore the grid and assess the gas infrastructure.

"We are now turning our minds more and more to the recovery effort," federal public safety minister Ralph Goodale said.

"This is going to be a long term endeavour because at the moment there is no power and gas, no palatable water supply. There's dangerous hazardous material all over the place. It's going to take a very careful, thoughtful effort to get that community back in a livable condition."

Ms Notley said the fire continues to grow outside the city and was about 787 square miles in size.

No deaths or injuries have been reported from the fire itself, but it has forced as much as a third of Canada's oil output offline and is expected to impact an economy already hurt by the fall in oil prices.

"We're just beginning to become aware of the economic impacts," prime minister Justin Trudeau said.

Alberta's oil sands have the third-largest reserves of oil in the world behind Saudi Arabia and Venezuela. Its workers largely live in Fort McMurray, a former frontier outpost-turned-city whose residents mostly come from elsewhere in Canada.