The amplitude and phase of temperature waves associated with plane progressive waves were determined in a laboratory experiment under a range of conditions, including wind speeds between 1 and 10 m/s and water-air temperature differences between 2.5¿C and 20¿C. Temperature waves were found, and at low wind speeds the results are in rough agreement with Witting's (1972) theory. However, the character of the temperature waves is strongly dependent on wind speed. Hence the amplitude and phase of the temperature waves change as the energy transfer across the air-water interface comes to be dominated by latent and sensible heat transfer at high wind speed. Radiation is the major mechanism of heat transfer at low wind speeds.