Elsewhere in the state, temperatures tied or broke records in 11 other cities and regions.
The National Weather Service issued both a Heat Advisory and a Red Flag wildfire warning for the Beehive State as the mercury sizzled higher. The Heat Advisory covered southwest and south central Utah, including St. George, Zion National Park and Lake Powell, with daytime highs of 110 to 115 degrees and overnight lows to range near 80.
The agency reiterated a warning about leaving pets or children in cars during the heat wave, even for short periods.
High-elevation thunderstorms and lightning, added to the high temperatures and tinder-dry condition of the high desert grasslands and forests, prompted a Red Flag warning over the mountains of eastern and central Utah.
The regional heat wave expected to send the mercury soaring to nearly 120 degrees in Phoenix and Las Vegas, threatening to ground airliners and raising fears that people and pets will get burned on the scalding pavement.
In June 1990, when Phoenix hit 122 degrees, airlines were forced to cease flights for several hours because of a lack of data from the manufacturers on how the aircraft would operate in such extreme heat. Smaller jets and propeller planes are more likely to be affected than big airliners, officials said.
Friday's heat was so punishing that rangers took up positions at trailheads at Lake Mead in Nevada to persuade people not to hike.
The mercury in Death Valley reached 122 degrees on Friday short of the 134-degree reading from a century ago that stands as the highest temperature ever recorded on Earth.
In Utah, in addition to the heat, there was another reason for residents of the northern part of the state to remain indoors: the Utah Division of Air Quality predicted degraded air quality for the weekend, rating Box Elder, Salt Lake, Davis, Tooele, Utah and Weber counties "Yellow," or compromised for breathability. Cache, Duchesne, Uintah and Washington counties earned "Green," or healthy air grades. #
Temperatures broke or tied records Friday in the following locations:
Alpine • 99, tied 1986 record
Alta • 80, broke 2002 record of 77
Cedar City Airport • 101, tied 1976 record
Escalante • 105, broke 1974 record of 101
Kanab • 105, broke 1984 record of 102
Milford • 104, broke 1984 record of 100
Provo, BYU • 103, broke 1994 record of 101
Randolph • 92, broke 1990 record of 87
Salt Lake City • 105, broke 1961 record of 102
Spanish Fork • 102, broke 1926 record of 101
Utah Testing Range • 100, tied 2002 record
Zion National Park • 114, broke 1950 record of 110