In Utah, a lightning-sparked fire consumed about 34 square miles, threatened a herd of wild horses and shut down the historic Pony Express Road in the state's western desert.
Along the Nevada-Oregon state line a vast wildfire has grown to about 675 square miles. Over the weekend, the blaze forced evacuations and forced one firefighter to crawl into an emergency fire shelter. She suffered minor burns and smoke inhalation, officials said.
Across California, thousands of firefighters also were contending with dry conditions, strong winds and triple-digit temperatures. The blazes left some areas with smoke lingering in the air.
In Northern California, hundreds of evacuees were allowed to return home as crews made progress against a wildfire that threatened 500 homes in the Spring Valley and Long Valley communities.
In Southern California, a cluster of four lightning-sparked wildfires in northeastern San Diego County stretched to nearly 4 square miles, state fire officials said.
Officials added there is also threat to electrical distribution lines that serve the communities of Borrego Springs, Warner Springs and Ranchita, some 50 miles northeast of downtown San Diego.
Fires across California have also affected some national parks with road and camp closures, including Lassen Volcanic National Park and Joshua Tree National Park.
Also, smaller blazes have been reported in New Mexico and Wyoming.