(Photo via inciweb.nwcg.gov)

The Finger Rock Fire on Aug. 5, 2015.

A wildfire burning in steep, rocky terrain in the Santa Catalina Mountains outside Tucson has led to a smoke advisory. Pima County officials say air quality monitors don't show elevated levels of particulate matter but smoke from the Finger Rock fire is visible.

The fire is burning in grass and brush but doesn't threaten any structures. On Wednesday it kicked up, due to wind and hot, dry weather. It grew to 500 acres on Thursday. Rain is forecast for the area on Friday.