Scorching heat Thursday will leave much of the Sun Belt sizzling, with temperatures hovering around 100 for tens of millions of people between the Texas Gulf Coast and California's Central Valley.
As many as 15 million people are under excessive heat warnings and 16 million more are under heat advisories across Arizona, Nevada and California.
The mercury in Houston is forecast to hit 98 degrees around 4 p.m. CT, which could break Space City's June 9 record of 97 degrees set in 2020.
Commuters in and around Sacramento, California, will have their car air conditioners on full blast with temperatures likely hitting 100 degrees between 4 p.m. and 6 p.m. PT.
Those cities could face even hotter temperatures this weekend with the thermometer in Phoenix expected to hit 113, 114 and 113 degrees Friday, Saturday and Sunday, respectively.
Excessive heat forced the Phoenix Parks and Recreation Department to close a pair of popular hiking trails.
It could be 110, 110 and 106 degrees in Las Vegas on those three days, and there's no relief in sight in Waco with temperatures expected to reach 103, 104 and 106 degrees.
It could 105 and 102 degrees in Sacramento on Friday and Saturday before finally dropping to a more tolerable 87 Sunday.
Even in regions where high heat isn't abnormal, too many people forget basic preventative measures like taking water with them on even short trips, Las Vegas fire spokesman Tim Szymanski said Thursday.
"That water can be precious and lifesaving," he said. "It's amazing how many people go out for a hike here (in extreme heat), it's ridiculous. They don't bring water with them and those end up being life-and-death situations. They'll be like, 'I'll just go down the trail for a half-mile' and they're overwhelmed in less than an hour."
There will also be millions of people under the threat of extreme storms.
A corridor of dangerous gusts are expected to plague the Texas Panhandle late Thursday afternoon before moving in the evening into Kansas, eastern Oklahoma, Nebraska and northwest Arkansas. The biggest cities in that region include Oklahoma City, Tulsa, Wichita, Amarillo and Norman.
Those storms and high winds are expected to move east and by Friday reach the Ozarks and the Gulf Coast, touching cities such as Mobile, Alabama; Little Rock, Arkansas; Shreveport, Louisiana; and New Orleans.