The power produced by a gas turbine system is augmented by a direct contact heat exchanger for contacting and cooling humid ambient air with cooler water for producing cooled ambient air and warmed water, and a precompressor device for compressing said cooled ambient air to produce pressurized air that is warmer than ambient air and has a lower relative humidity. An evaporative cooler, which is supplied with the warmed water, is provided for cooling said pressurized air to produce cooled pressurized air at about ambient air temperature and relative humidity, which is supplied to the main compressor.