The so-called Oak Fire was started by lightning on June 17.
It's burning mainly in timber and brush in the Galiuro Mountains southwest of Safford.
Authorities say the wildfire is being managed to benefit the environment in the Coronado National Forest.
It's expected to continue burning until monsoon storms arrive.
The Arizona Daily Star reports that several fire crews, engines and a helicopter are assigned to the fire but the blaze isn't actively being fought.