A fire straddling the Nevada-Idaho border increased by about 25 percent in one day.
The Holloway Fire grew to 152,110 acres or about 238 square miles as the fire roared through dry sagebrush and grass pushed by wind and unimpeded by low humidity, said fire public information officer Marian Swinney.
In terms of acres, the Holloway Fire is the ninth largest active fire in the United States listed on the federal Incident Information System.
The fire is burning between Denio and McDermitt in Nevada and goes up to White Horse Road in Oregon, Swinney said.
The temperature in the area was 100 on Thursday.
"It's supposed to cool down by Monday," Swinney said.
The fire is 5 percent contained and is expected to be fully contained by Aug. 22, Swinney said.
No buildings have been lost but eight homes and 27 outbuildings are threatened along with power lines, communication towers and sage grouse habitat, Swinney said.
The cost of fighting the fire is estimated to be $1.6 million. There are 343 fire personnel on the fire.
The Lost Fire in northern Washoe County increased to 59,200 acres and is 30 percent contained, fire public information officer Rebecca Franco said.
Lightning started both fires on Sunday.