Canadian Wildfires Could Intensify from a Looming Heat Wave.

As Canada battled wildfires from its west coast to the prairies, another blistering heat wave threatened to descend this week on British Columbia, where more than a million acres have burned since April.

In recent months, a series of near-relentless heat waves and a deepening drought linked to climate change have helped to fuel exploding wildfires.

In Manitoba, a drought has forced livestock farmers to consider selling some or all of their cattle. With rising temperatures in the forecast, northwestern Ontario is also bracing for a possible outbreak of fires later this week, its provincial forest fire service said in a Twitter post.

The risks from these fires was illustrated in southern Oregon, where the Bootleg Fire grew so large and hot that it created its own weather, triggering lightning and releasing enormous amounts of smoke.

Hot and dry conditions expected this week could expand the infernos, Forrest Tower, a spokesman for the British Columbia Wildfire Service, said in an audio clip released by the department on Sunday.

Near the southern part of the province, the Okanagan region, about 200 miles north of the Washington border, a fire that hasburned uncontrollably since July 13 now encompasses more than 137,000 acres, the wildfire service estimates. Close to 300 firefighters, along with more than a dozen helicopters and other heavy machinery, are fighting the blaze, but so far have failed to subdue the flames.

Temperatures in British Columbia’s interior region could surpass 90 degrees Fahrenheit later this week,said Bobby Sekhon, an emergency preparedness meteorologist with Environment and Climate Change Canada, a government agency. High temperatures could make it more difficult to extinguish the fires, as seen in the record-breaking June heat wave, when crews in British Columbia grappled with overheated helicopter engines and other machine failures.

“It’s not nearly as intense as what we saw at the end of June,” Mr. Sekhon said, when temperatures exceeded 120 degrees Fahrenheit in places. “Nonetheless, we’re looking at potentially our third set of heat warnings for this summer, which is a lot more than we’ve seen in the past couple of summers.”

Wildfire smoke from Canada and the Western United States stretched across the continent last month, covering skies in a thick haze and triggering health alerts from Toronto to Philadelphia, with officials in some places recommending that people stay indoors with their windows closed.

Across the Pacific Northwest, fires have become more extensive and more frequent in recent years, threatening the lives and livelihoods of residents and disrupting a tourism industry that relies on clear skies and fresh air.

Local governments and Indigenous communities in British Columbia’s fire-stricken regions have issued evacuation alerts, asking residents to pack essential items, documents and keepsakes, plan the transportation of pets and livestock and have full tanks of fuel in their cars in case ordered to flee to safety.

About 32,500 properties are under evacuation alerts in British Columbia, the province said in a bulletin Monday, whileresidents in more than 6,500 other properties have already been ordered to evacuate. The province currently has 273 active wildfires, the bulletin notes, amid a total of 1,445 since April that have burned more than 1.5 million acres.

The total number of wildfires in Canada this year has already exceeded the country’s 10-year average by at least 30 percent, with months left in the fire season, according to data published by Natural Resources Canada.

The wildfires scorching areas of Canada and the United States in recent years may be only the beginning of the areas’ woes, according to a new United Nations scientific report. The extreme weather seen around the world, including droughts, heat waves and flooding, will likely worsen for at least the next 30 years, the report says, because of climate change induced by human activity.

Kim Connors, executive director at the Canadian Interagency Forest Fire Centre, a coordinating authority for firefighting resources, said the country saw a similar wildfire situation in 2017. But this year, he said, the wildfires cover an enormous area, everything “west of the Great Lakes, which includes the province of Ontario, to the Pacific Ocean.”

As a result, he said, the authorities cannot free up resources to concentrate on the major fires. The problem has beenmagnified by cutbacks in aid and resources from the United States, because of its own battle with wildfires, and countries like New Zealand and Australia, which have been unable to dispatch crews because of pandemic travel restrictions.