Described herein are glass forming apparatuses with cooled muffle assemblies and methods for using the same to form glass ribbons. According to one embodiment, a muffle assembly for a fusion forming apparatus may include a muffle frame comprising a back wall, a front wall opposite the back wall, and a pair of sidewalls joining the front wall to the back wall in a closed-loop. At least one first cooling tube may extend through the back wall and the front wall across the closed-loop. At least one second cooling tube may extend through the back wall and the front wall across the closed loop such that the at least one second cooling tube is spaced apart from and parallel with the at least one first cooling tube.