California, Nevada, Arizona, New Mexico, Colorado, Utah, Idaho and Montana all reported higher than normal temperatures. Authorities in numerous states issued warnings for everything from fire danger to energy use to dehydration and even to be on lookout for hungry bears.
With some areas of Colorado seeing almost double the number of days with 90-plus temperatures this year, bears have seen their natural food supply dry up, forcing them to forage in human habitats.
In Phoenix, a desert city well accustomed to blistering summer temperatures, record highs were set three days last week. Temperatures on Wednesday hit 116. This weekend, the thermometer is expected to hit around 113. Homeless people are flocking into the city's shelters, which have opened up extra beds to accommodate up to 150 additional people Saturday night.
"People just can't stand to be outside anymore," said Irene Agustin, development director for Central Arizona Shelter Services.
The city of Los Angeles kept municipal pools open through the weekend and encouraged residents without air conditioning to use recreation buildings as "cooling centers."
Those who could get out of town did. Water spots from lakes to rivers to beaches and highways leading to them were packed Saturday with people seeking heat relief.
George Medici, a Los Angeles public relations executive, drove an hour north to beat the heat at a coastal golf course in Oxnard, Calif. Even with gas at $4 a gallon, it was well worth it, he said.
"It was 106 degrees when I left the [San Fernando] Valley," he said. "Here's it's 79. It's a pretty wild thing."
The hot, dry weather has put firefighters across the region on heightened alert.
Red flag warnings were in effect for a wide swath of Northern California, with forecasters predicting temperatures to break 100 across much of the area.
Idaho has already seen a jump in forest fires this summer, which has caused a related health concern exacerbated by the heat drifting smoke. "With all the fire activity, we're having air quality issues," forecaster George Skari said.
Reno, Nev., is looking at the hottest month on record if the trend keeps up, meteorologist Scott McGuire said.
San Diego was bracing for another consequence of the extreme heat severe thunderstorms. The National Weather Service urged residents to stay inside a storm could drop quarter-sized pellets of hail.