Devices, systems, and methods for degassing fluid prior to applying fluid to a treatment site during ablation therapy are provided. In one embodiment, an ablation system can include an elongate body, an ablation element, a heating assembly, and a fluid source. Fluid in the fluid source can be at least partially degassed prior to being provided as part of the system, or, in some embodiments, a degassing apparatus can be provided that can be configured to degas fluid within the system prior to applying the fluid to the treatment site. The degassing apparatus can include one or more gas-permeable and fluid-impermeable tubes disposed therein, which can allow gas to be removed from fluid passing through the apparatus. Other exemplary devices, systems, and methods are also provided.