While many of the blazes are in remote areas, they threaten some ranches and Iowa Hill, a remote mountain hamlet in California that dates back to the Gold Rush era, authorities said.
Two fires, both believed started by lightning strikes, were burning in northwest Utah, The Salt Lake Tribune reported.
The Meadow Fire, which has been burning since Tuesday, had spread to 1,500 acres was about 10 percent contained, Teresa Rigby, a spokeswoman for the Interagency Fire Center, reported. The Rhyolite Fire, which was reported Wednesday, was still uncontained at 1,200 acres.
Two larger fires in the state were close to full containment. John Zapell, a fire information officer, said firefighters working the 108,000-acre Clay Springs blaze were focused on hot spots.
The Seeley fire in the Manti-La Sal National forest, had spread to almost 48,000 acres. Full containment was expected by Sunday.
In Arizona, four small fires were burning in the Tonto National Forest. By late Wednesday, they had spread through a total of 310 acres, The Arizona Republic reported.
Firefighting efforts were hampered by the remote difficult terrain.
In California, a fire on the western slope of the Sierras about 80 miles northeast of Sacramento spread from 200 to 220 acres overnight, the Sacramento Bee reported. The blaze was reported Wednesday afternoon.
Daniel Berlant, a spokesman for the state Department of Forestry and Fire Protection, told the Bee the cause was still under investigation and would not confirm reports it was started by fireworks.
Iowa Hill, with a population of 200, was threatened by the fire. Officials also worried it could jump the American River and head toward Colfax, a town of 2,000 on I-80.