More than 50 million people from southern Arizona to northern Montana were under heat alerts Tuesday as relentless heat continued across the Western United States.
For some areas — including Death Valley, Phoenix and Las Vegas — temperatures could reach 110 to 130 degrees.
During the recent heat wave, which has lingered for nearly a week, more than 700 daily record highs have been set, most of them west of the Rocky Mountains.
The heat event is the same one that caused Death Valley to live up to its name as the Hottest Place on Earth, with temperatures soaring to an exceptional 130 degrees Sunday. And that was the air temperature. High-resolution satellites registered the land surface temperature as above 140 degrees.
It was the first time Death Valley has been that hot in 107 years, since 1913. If verified, it will be the third hottest temperature ever recorded on Earth, and it could be the hottest, before the only two hotter temperatures are under scrutiny: 134 degrees in Death Valley in July 1924 and 131 degrees in Kebili, Tunisia, in July 1931.
The heat is expected to diminish by Friday, but not before 60 to 70 more daily record highs could be broken or tied. Some cities forecast to set, tie or come close to setting records Tuesday were Denver, Las Vegas, Phoenix, Sacramento, California, and San Francisco.
Heat waves are getting hotter, longer and more frequent because of climate change. Las Vegas is the fastest warming city in the United States, with Phoenix; Tucson, Arizona; Las Cruces, New Mexico; and El Paso, Texas, all making the Top 10.
In addition to blistering temperatures, parts of the West continued to deal with a fire threat. Red flag warnings — meaning the conditions are favorable for wildfires to spread — were up for parts of Oregon, Idaho, Wyoming and Montana, while fire weather watches were issued for parts of Idaho, Montana, California, Nevada and Colorado out of concern over extreme fire behavior.
The hot temperatures, combined with low humidity and gusty winds over 50 mph, will make conditions favorable for fire ignition and spread. The highest risk for fires Tuesday is across parts of eastern Oregon, Idaho and western Montana.
Fire crews continued working Tuesday to contain the Lake Fire in Southern California, which covered more than 19,000 acres and was 38 percent contained.
The Pine Gulch Fire in Colorado was up to 86,120 acres and 7 percent contained. It has become the fourth-largest wildfire in Colorado history, and it could soon become the third largest.
The 10 largest recorded wildfires in Colorado history have all occurred since 2000.