An information handling system (IHS) cooling system includes an IHS chassis defining an IHS chassis air inlet. A cooling chassis supports the IHS chassis on a support base. An air supply duct extends from the cooling chassis such that an air supply duct outlet on the air supply duct is immediately adjacent the IHS chassis air inlet. An air cooling subsystem is located in the cooling chassis and is operable to cool air that is drawn into the cooling chassis and supply the cooled air to the IHS chassis air inlet through the air supply duct. The IHS chassis may be a conventional IHS chassis that is designed for sub-35 degree Celsius ambient temperatures, and the cooling chassis may be provided for the conventional IHS chassis when used in extreme environments with high ambient temperatures above 35 degrees Celsius.