Parts of Idaho, Wyoming and Montana are under warnings for dry storms that could spark new fires, CNN meteorologist Chad Myers said Wednesday.
The National Weather Service issued "red flag warnings" for these areas Wednesday for the third day in a row.
That means there are likely to be storms in which the only thing that reaches the ground is the lightning, Myers said. Most or all of the rain evaporates on the way down, leaving the lightning to strike the hot, dry earth.
Winds of up to 60 mph will accompany some of the storms, adding to the risk of new fires, he added.
It's hotter than usual in those Northwestern regions, but temperatures pale in comparison to those in the desert regions of Arizona and California, which face excessive heat warnings Wednesday for the second day in a row.
The triple-digit temperatures will strain air conditioners and force residents to find creative ways to stay cool.
A city park's water feature looked inviting to Shariee Walles, who gets around in a motorized wheelchair.
"I'm not supposed to take my chair through the water, but I'm just so hot that I don't care," she told CNN affiliate KLAS-TV in Las Vegas, where the city tied a record high of 114 degrees Tuesday.
Cooling centers were open across the city for a second day, but they largely sat empty Tuesday.
Clark County spokesman Dan Kulin said they will remain open another day even if no one is using them.
"We'll still stay open for anyone that needs it," he said, according to KLAS.
The brutally hot weather is hard on cars, but great for business at auto repair shops -- radiators burst, tires go bad.
"Batteries go bad in the heat a lot, too," Dave Ford, at a car shop in Henderson, Nevada, told CNN affiliate KTNV. "Especially when it spikes."
And spike it did, especially along the famous Las Vegas strip, where CNN affiliate KVVU measured the sidewalk temperature at nearly 150 degrees.
"I can feel the heat burning my legs off the cement," one tourist said.
Despite most folks craving the cool of the indoors, some prefer to be outside, even in the heat.
In Phoenix, also under an excessive heat advisory, the city's sign spinners -- the guys trying to coax you into local business with their creative roadside advertising methods -- think it's "cool" to be hot.
"In our case, we're ready for the job," Mark Montellano of AArrow advertising told affiliate KPHO. "We work in the heat, practice in the heat ... so ... we're mentally and physically prepared to work, and enjoy it every time."
Wednesday's National Weather Service forecast called for highs of 125 in Death Valley, California; 112 in Las Vegas; and 109 in Phoenix.
The heat is also taking its toll in the nation's Northwest.