(CNN) -- 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.
It's been more than a month since Jerry Mann's 9,000-acre farm has gotten rain, and when the 56-year-old Montana man examines the dry, shriveling kernels of wheat and barley, he's understandably nervous.
"We're looking at a 30 to 40% drop in the usual yield if we don't get some rain here real soon," he said.
The high Tuesday in Great Falls, Montana, was 95, a number not quite as high as the triple digits seen in other parts of the country, but one that presents major problems for its residents -- particularly those involved in agriculture.
The temperatures are up to 15 degrees above normal in Northwestern cities such as Great Falls, CNN meteorologist Sarah Dillingham said Tuesday.
Mann knows the land and knows the crops. He was born into farming, and on that land he's raised wheat, barley and a family.
A 30% to 40% drop in yield is likely to mean a 30% to 40% drop in income, depending on whether there is a shortage that will affect prices.
"You worry," he said, sighing. "But there's nothing you can do about it."
The heat came early this year, but it isn't uncommon for Montana temperatures to swing wildly, said Great Falls Fire Chief Randall McCamley. It's one of the things he likes about the city, where he has lived for 30 years.
"We can break a record high and a record low on the same day here," he said. "It keeps us guessing."
Though untimely, the temperatures in Montana haven't caused any heat-related deaths, state officials said.
But at least 51 people elsewhere in the United States have died from heat-related -- or heat-exacerbated -- causes in the past two weeks. It is difficult to determine an exact number because of a lag time in official counts and differences in the states' standards.
CNN's Melissa Abbey contributed to this report.