With record-breaking temperatures and hard-to-contain wildfires, Western states are struggling through a hellish summer.

By Giulia HeywardPublished July 11, 2021Updated July 12, 2021, 10:15 a.m. ET

As the West continues to bake under torrid temperatures, an out-of-control wildfire burning across southwest Oregon has scorched more than 150,000 acres, threatening the power grid that connects Oregon and California and driving people from their homes.

The Bootleg fire continued to burn for its sixth day in a row on Monday. The intense blaze escalated on Saturday afternoon, leading firefighters to leave the scene and retreat back to safety because of an “immediate, life-threatening risk,” according to one update from fire officials.

Charles Smith, a meteorologist with the National Weather Service in Medford, Ore., said the fire was especially worrying because Oregon’s fire season had only just begun.

“There’s concern because of how early this is starting, and how far it has grown within a relatively short amount of time,” he said.

The Bootleg fire’s intensity at this early stage in Oregon’s fire season has officials calling it “unprecedented.”

“The fire is changing so dramatically — in the past couple days, it’s doubled in size,” said Mark Enty, a spokesman for the Northwest Incident Management Team 10, which is working to contain the fire. “It’s going to take a long time before it’s safe for people to return.”

There have been no human fatalities or injuries from the blaze, Mr. Enty said.

As the Bootleg fire continued to grow over the weekend, it burned across a voltage power line corridor, threatening a major power grid, Path 66, that connects Oregon and California.

The presence of wildfires, including the Bootleg fire, has put pressure on California’s electrical system, leading to an emergency that is just a step away from rolling blackouts.

Gov. Gavin Newson of California signed executive orders on Friday and Saturday allowing the use of backup generators and auxiliary ship engines for power to ease the state’s dependency on the electric grid.

“We’ve had extremely dry conditions in the southern part of Oregon since the spring,” said Brian MacMillan, a meteorologist and reporter for KPTV, a Fox affiliate in Portland. “It’s one of the driest, if not the driest, spring in record.”

The megafire in Oregon was just one hot zone across the western United States as a “dangerous heat wave” over the weekend was expected to continue into Tuesday, according to the National Weather Service. It is the third heat wave to hit the region so far this summer.

The scorching heat included a 130-degree reading in Death Valley in California on Friday, matching a similar recorded temperature in August 2020. The temperature in the area reached just over 120 degrees on Sunday.

Dangerously hot conditions, with temperatures ranging from 100 to 118 degrees, are expected in the western Mojave Desert and Owens Valley, in California, and throughout parts of western and south-central Nevada, including Las Vegas, in Clark County, until Tuesday.

Before the heat wave struck, cooling centers popped up across California. Portable air-conditioning kits reportedly sold out in stores in Salem, Ore., in June. Both restaurants and outdoor Covid-19 vaccine clinics closed in Portland.

The Bootleg fire began in the Fremont-Winema National Forest near the Sprague River on Tuesday, just before 2 p.m., according to an incident report. While the megafire began in a relatively remote area, it soon traveled closer to homes, leading in Klamath County to a Level 3 evacuation, meaning that residents should leave immediately because danger is imminent.

The Sheriff’s Office there said it also “took the rare step of citing or arresting those who remained in or were trying to re-enter the Level 3 evacuation areas in the Bootleg fire area.

This summer, with its record-breaking temperatures, heat waves have already killed 78 people since late June in Washington State, and another 116 people in Oregon. Homeless people and those who were sick or older make up a significant portion of the death toll.

Oregon was not the only state battling wildfires over the weekend.

In California, the Beckwourth Complex Fire, which started by lightning, had consumed more than 86,000 acres in Plumas National Forest and was 20 percent contained as of Monday morning. It jumped a major highway, U.S. 395, on Saturday, while photos and videos showed buildings, cars and hillsides entirely engulfed in flames.

Separately, the River Fire in Mariposa County had burned through 4,000 acres and was 5 percent contained as of Monday morning, forcing several evacuations and road closures.

On Saturday, two people assisting in containing a wildfire in western Arizona died after their plane crashed. They were “performing aerial reconnaissance and command and control” over the Cedar Basin fire, which started near Wikieup, Ariz., and had covered over 700 acres as of Sunday, according to an incident report.

Plane crashes continue to be a common occurrence during wildfires. A pilot who was assisting in a wildfire in Idaho died in September, and three Americans were killed in January when their plane, filled with fire retardant, went down in the mountains south of Canberra, in Australia.

Aircraft are being used to help contain the Bootleg fire.

Fire officials have now turned to adding more firefighters to the night shift, during which they say weather conditions will be better for containing the blaze.

While experts and officials are not sure how long the Bootleg fire will burn, both it and the heat wave have no end in sight.

“We don’t see any rain in the forecast anytime soon,” Mr. MacMillan said.

Austin Ramzy and Daniel Victor contributed reporting.