A drilling mud cooler includes a first mud heat exchanger that is adapted to receive a flow of drilling mud, a first closed-loop cooling system that is adapted to cool a first cooling fluid that is circulated through the first mud heat exchanger so as to reduce a temperature of the flow of drilling mud from a first temperature to a second temperature, a second mud heat exchanger that is adapted to receive the flow of reduced temperature drilling mud from the first mud heat exchanger, and a second closed-loop cooling system that is adapted to cool a second cooling fluid that is circulated through the second mud heat exchanger so as to further reduce the temperature of the flow of drilling mud from the second temperature to a third temperature.