The heat will be on "high" in the Desert Southwest the next several days.
Temperatures are expected to soar well over 110 degrees in portions of Arizona, Nevada and California by the weekend and into early next week, the National Weather Service warned.
Many desert locations, including Phoenix, could climb as high as 115 to 120 degrees Sunday through Wednesday, the weather service said. That could rival the all-time high temperature of 122 degrees set at Phoenix Sky Harbor Airport in 1990.
Notorious hot spot Death Valley, home to the world's all-time hottest temperature of 134 degrees, will soar to 123 degrees by Sunday. Nights won't provide much relief: the low temperature will drop to only the low 90s.
Heat will also scorch the central valley of California, where cities such as Bakersfield, Fresno and Sacramento will see highs over 100 degrees.
The weather service issued several heat alerts for southern Arizona, southern Nevada and much of California. "Very hot temperatures will significantly increase the potential for heat-related illness," the weather service said.
Those most at risk include people working or exercising outdoors during the daytime, the elderly and those without access to adequate air conditioning, the weather service warned. "Untreated heat illness can lead to fatal heat stroke," it said.
Hot spells in the Southwest this time of year aren't unusual: Many locations in the region see their hottest readings, on average, from the latter half of June into early July, when the air is still extremely dry, weather.com said. By mid-July and into August, when the summer monsoon kicks in, temperatures decrease as humidity, clouds and showers increase.
As is typical during these heat waves, low clouds and sea breezes will keep immediate coastal areas from the worst of the broiling heat. Cities such as Los Angeles, San Diego and San Francisco will see highs in the 70s and 80s.