An evaporative cooling system for a radiator and method for retrofitting an existing radiator with an evaporative cooling system is provided. The cooling system includes at least one spray nozzle configured to be connected to the radiator upstream of a radiator core and configured to distribute a mist of water to the radiator core; a water source configured to hold water for conveyance to the at least one spray nozzle; and a conduit assembly for conveying water from the water source to the at least one spray nozzle. The evaporative cooling system provides a quick and inexpensive solution for cooling radiators in situations where short-term extreme temperature events occur.