A first aspect provided herein relate to a method of controlling cathode exhaust humidity. The method can include receiving, by a cathode controller, a signal indicating a sensed humidity of a cathode exhaust from a fuel cell of a machine. The method can include determining, by the cathode controller, that the sensed humidity is outside of a predetermined range. The method can include adjusting, by the cathode controller, one or more control parameters, to cause the fuel cell of the machine to produce cathode exhaust having a humidity within the predetermined range.