The fire broke out in an alley near the 600 block of South 14th Avenue just after noon. It began in a pile of garbage before spreading to the garage. Firefighters were able to contain the fire in about five minutes.
The building received heat and smoke damage valued at about $15,000.
No one was injured in the fire.
The Yakima Fire Department says all three fires in the area have been started by burning garbage in alleys. Firefighters recommend that people in the area keep their trash in appropriate containers and in well-lighted areas.
YFD is looking for the person or persons responsible for the string of fires. Anyone with any information is asked to call (509) 575-6060.