Shifting winds gusting to 40 kilometers per hour (25 miles per hour) fanned the flames, scorching 9,600 hectares of surrounding forests as it advanced to within 13 kilometers (eight miles) of the city that had previously been gutted by wildfires in 2016 -- one of the biggest disasters in the nation's history.
Thousands of residents in the neighborhoods of Prairie Creek, Abasand, Grayling Terrace and Beacon Hill were ordered out by 4 pm local time. By mid-afternoon, a highway south was jammed with cars and trucks.
"We're seeing extreme fire behavior," Alberta Wildfire spokeswoman Josee St-Onge told a news conference.
"Smoke columns are developing and the skies are covered in smoke," she said. "Firefighters have been pulled from the fire line for safety reasons."
Officials said the fire had grown significantly in multiple directions since Monday.
Regional fire chief Jody Butz, however, assured residents that crews were prepared, having cleared brush and erected fire barriers over the winter, and that water bombers were now dropping retardant to slow its advance.
"We are confident that we have the resources to defend these areas, but we need people out of harm's way," he said.
Authorities have been bracing for another possibly devastating wildfire season, after Canada's worst ever last year that saw flames burning from coast to coast and charring more than 15 million hectares (37 million acres) of land.
Dozens of zombie fires sustained by layers of dried peat continued to smolder beneath the surface of the boreal forest through the winter, which was warmer than usual and left a smaller snowpack, while drought has persisted across the region.
In British Columbia, thousands of residents of remote towns remained under evacuation orders, while CN railway on Tuesday suspended rail service between Fort St. John and Fort Nelson, and north of High Level in Alberta "due to wildfire activity."
Rob Fraser, the mayor of Fort Nelson, from a nearby perch told AFP: "It's cool, it's overcast and the wind is just very slight. If everything continues like this, you know, we just might corral this beast."
Air quality warnings, meanwhile, have been issued across Canada and the United States as plumes of smoke from the Canadian wildfires wafted as far south as the US state of Oklahoma and over to Quebec province in the east.
