More than 170 people were treated for heat-related ailments and some towns and cities took emergency steps to protect the homeless and elderly as the West sweltered on Saturday in dangerous near-record, triple-digit temperatures.
Extreme heat enveloped most of California and Nevada and parts of southern Arizona as a large high pressure system trapped hot air across the area, said National Weather Service meteorologist Todd Lericos.
More than 170 people were "treated for heat-related injuries" and 34 more were sent to local hospitals while attending an outdoor concert on Friday afternoon in Las Vegas, Nevada, where temperatures soared to 115 degrees Fahrenheit (46 C), said Erik Pappa, a spokesman for Clark County. On Saturday, highs are expected to reach 117 (47 C).
"It involves pretty much the entire West Coast at this point," Lericos said, adding that the steamy conditions, which began in some pockets on Thursday afternoon, will likely continue throughout the weekend and linger into next week.
Temperatures were well into the triple-digits in most of the area, except in higher elevations.
In Death Valley, one of the hottest places on earth, temperatures could soar on Saturday to 128 F (53 C), close to the daily record set in 1994. Other areas in and around the Mojave Desert will see triple-digit temperatures.
The "exceedingly high temperatures" can cause potentially fatal heat stroke, Lericos said, noting that those with no air-conditioning or who must work outdoors were particularly at risk.
In an effort to safeguard hundreds of homeless in Phoenix, where temperatures could hit 120 F (48 C) on Saturday, emergency shelters are temporarily adding 150 beds.
The National Weather Service said the heat warning remains in place through Sunday, and could be extended into next week should the conditions persist.
Areas in the more temperate Pacific Northwest, such as Seattle and Spokane, Washington, and Pendleton, Oregon, face hot weather over the weekend and early next week as the heat moves northward, Lericos said.