Wildfires were burning across more than 768,000 acres of land in 12 western U.S. states, and over 500,000 acres in Canada on Sunday amid another searing heat wave.
Driving the news: Many of the wildfires started when a severe heat wave erupted in June and lasted into July, first hitting southwestern British Columbia before migrating eastward.
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The severity of the extreme weather event has been pinned on human-caused global warming, and climate change is also heightening the risk of wildfires in the U.S..
The typical heart of the Canadian wildfire season doesn't arrive until August, when vegetation is at its driest, but the heat has sped that process along.
By the numbers: Firefighters were battling 55 large fires across the U.S. on Sunday — including 11 in Arizona, 10 in Idaho, nine in Montana, six in California and five in Oregon, according to the National Interagency Fire Center.
In Canada, firefighters were responding to more than 300 active wildfires, including 60 new ones, per the CBC.
What's happening: Evacuation orders and warnings were issued in states including California, Oregon, Idaho and Montana, as well as British Columbia. Smoke from the fires was bringing hazy skies to large parts of the western and central U.S.
The biggest wildfire to hit the U.S. so far this year, the Beckwourth Complex fire, near California's border with Nevada, forced the temporary closure of U.S. Highway 395 late Saturday.
The blaze, the combination of two fires sparked by lightning in the Plumas National Forest, expanded by a third to 134 square miles Sunday — though firefighters working in heat topping 100°F managed to increase containment to 20%, AP notes.
In Arizona, two firefighters died on Saturday when their aircraft crashed while responding to a wildfire in Mohave County, per a Bureau of Land Management statement.
Of note: Canada's Interagency Forest Fire Center elevated its readiness level to 5 — the top of its scale, noting "active agencies may take emergency measures to sustain incident operations."
The move reflects the enormity of the firefighting challenges facing the heavily forested nation, with dozens of fires burning from temperate rainforests to the boreal region ringing the Arctic.
Editor's note: This article has been updated with new details throughout.
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