A wildfire so ferocious it was nicknamed "the Beast" has finally been tamed.

The fire that destroyed some 2,400 buildings in Fort McMurray, Alta., and forced the evacuation of the entire city is now classified as "being held," officials said Monday.

The classification means the fire is not yet under control but is no longer expected to grow.

"It's a huge breakthrough," said wildfire information officer Lynn Daina. "It's been out of control for so long. This is the first very significant change that we've had, so everyone is very pleased."

The fire hit Fort McMurray on May 3 and forced more than 80,000 people from their homes. At its peak, the fire moved at 30 to 40 metres per minute and created its own weather patterns. A black funnel cloud emanating from the heart of the flames became so monstrous it was visible from space.

Although the fire now covers more than 589,617 hectares, with a perimeter of 1,080 kilometres, 82 per cent of the blaze has been contained.

Daina said damp weather and six weeks of hard work have helped firefighters gain the upper hand.

More than 1,000 firefighters are still working the front lines, and after weeks of dry conditions, a change in the weather over the last two weeks has dumped 57 millimetres of much-needed rain on the region.

"The priority right now is just to keep it at 'being held' and work our way in, and make sure all those hot spots are being extinguished."