Abstract: A multi-stage hybrid evaporative cooling system is described as having a direct evaporative cooling subsystem and an indirect evaporative cooling subsystem having one of a horizontal and a vertical set of heat exchanger channels. The multi-stage hybrid evaporative cooling system with a horizontal set of heat exchanger channels has a portion of the horizontal heat exchanger channels partially extended into a next stage of the multi-stage system. The multi-stage hybrid evaporative cooling system with the vertical set of heat exchanger channels includes a first set of vertical set of heat exchanger channels spanning a substantial vertical height of the stage of the hybrid evaporative cooling system, and a second set spanning approximately half the height of the stage. The multi-stage hybrid evaporative cooling system further includes a refrigeration system for lowering the temperature of the indirect evaporative cooling subsystem air without affecting its pressure flow.