A judge also ordered him to pay $10,000 in restitution, the cost of the school's insurance deductible.
The teen was remorseful and apologized for his actions in court on Wednesday morning.
The fire started after he lit a stack of napkins on fire in a band storage room.
The flames then spread, causing $800,000 in damage.
More than 3,000 students, along with faculty and staff, were evacuated. There were no injuries.