Staff members are returning to Alberta oil installations after emergency service officials cleared the area of major wildfire threats, Cenovus Energy said.

Rain is expected through the end of the week in Calgary, the nation's forecaster said. Hot, dry weather led provincial authorities in May to issue an open-fire ban to curb the spread of wildfires in Alberta. As of Friday, more than 43,000 hectares have burned, though only five of the 41 active fires are considered out of control.

Cenovus Energy said its crews were working to restore power to its Foster Creek oil sands operation, which has the capacity to process 135,000 barrels of oil per day. Foster Creek was closed by fire in late March.

"A small group of Cenovus essential staff has restored power on our site," the company said in a statement. "We're currently inspecting our facilities and re-starting our control, security and safety systems."

Canadian Natural Resources said Monday it was cleared to return to its operations at oil installations on the Cold Lake Air Weapons Range. A step-by-step recovery plan is under way, "including the inspection of facilities and equipment, and the completion of repairs, if required," the company said.

Fires were as close to three miles from the company's Alberta operations, though provincial authorities said there was no immediate risk to its infrastructure. Authorities stressed the risk of fires continues, however, despite the break in the weather.

"We will continue to monitor the progress of the forest fire on the Cold Lake Air Weapons Range and take any necessary steps to protect the safety of our workers," Cenovus added.