Namtheun was a C1 tropical cyclone that formed in the East China Sea in 2004. The storm reached maximum sustained winds of 157 km/h (85 kt) with a minimum central pressure of 935 hPa. Tracking across the East China Seain the Western Pacific basin (, it potentially affected Japan, Korea, Taiwan and eastern China. The storm traveled from approximately 20.1°131.1° to 36.0°150.8°, crossing a range of 16 latitude and 20 longitude.