Spokeswoman Heather Noel says no structures are threatened by the growing Jack Fire that was reported around 11:40 a.m. Saturday.
The fire is burning about 13 miles northeast of Happy Jack in a canyon near State Route 87. The rock-climbing area in Jack's Canyon was evacuated and closed.
Noel says firefighters put a line around the right flank of the fire. Aircraft dropped retardant on the left side, and crews are trying to set up a line. About 90 firefighters will work into the night ahead of 24 mph winds expected Sunday morning.
The cause of the fire is under investigation.