Firefighters have struggled to contain an exploding northern California wildfire under blazing temperatures as another heatwave blankets the western United States, prompting an excessive heat warning for inland and desert areas.
Death Valley in southeastern California's Mojave Desert reached 53C on Saturday, according to the National Weather Service's reading at Furnace Creek. The shockingly high temperature was actually lower than the previous day, when the location reached 54C.
If confirmed as accurate, the reading would be the hottest high recorded there since July 1913, when Furnace Creek desert hit 57C, considered the highest measured temperature on earth.
About 480 kilometres northwest of the sizzling desert, the largest wildfire of the year in California was raging along the border with Nevada.
The Beckwourth Complex Fire - a combination of two lightning-caused fires burning 70 kilometres north of Lake Tahoe - showed no sign of slowing its rush northeast from the Sierra Nevada forest region after doubling in size between Friday and Saturday.
Late on Saturday, flames jumped Interstate 395 and were threatening properties in Nevada's Washoe County. "Take immediate steps to protect large animals and livestock," the The Truckee Meadows Fire Protection District tweeted.
The blaze, which was only 8 per cent contained, increased dramatically to some 220 square kilometres as firefighters sweltered.
It was one of several threatening homes across western states that were expected to see heat through the weekend as a high-pressure zone blankets the region.
Pushed by strong winds, a wildfire in southern Oregon doubled in size to 311sq km on Saturday as it raced through heavy timber in the Fremont-Winema National Forest near the Klamath County town of Sprague River.
Las Vegas on late Saturday afternoon tied the all-time record high of 47C, the National Weather Service said. The city has recorded that record-high temperature four other times, most recently in June 2017.
In Southern California, a brush fire sparked by a burning big rig in eastern San Diego County forced evacuations of two Native American reservations Saturday.
A wildfire in southeast Washington grew to almost 155sq km as it blackened grass and timber while it moved into the Umatilla National Forest.
In Idaho, Governor Brad Little declared a wildfire emergency Friday and mobilised the state's National Guard to help fight fires sparked after lightning storms swept across the drought-stricken region.