The National Weather Service said any new wildfires were expected to exhibit "extreme fire behavior," NBC News reported.
More fires could start in parts of Utah and Idaho, the weather service said, after the National Interagency Fire Center said Wednesday five large new fires had been reported in Idaho, Utah, Wyoming and Montana.
Wildfires are also burning in Oregon, California and Washington. Dangerous conditions expected in Hawaii prompted officials there to leave a fire warning in effect.
The Elk Complex wildfire in Idaho was only 25 percent contained after burning almost 112,000 acres, the Forest Service said Thursday. The service said the fire is not expected to be fully contained until Oct. 1.
Near Park City, Utah, the Rockport 5 wildfire had grown to more than 2,000 acres by Wednesday evening. It was only 25 percent contained.
The fire center said 3,073,404 acres had been torched by wildfires since the first of the year. During the same period in 2012, 6,016,199 acres burned.