DE 2 Wind And Temperature Spectrometer (WATS) instrument data has been analyzed to investigate supersonic excursions of the measured neutral wind. There have been 488 supersonic events identified, with the zonal component of the neutral wind Mach number M in the range 1 < M < 2. These events are located in the polar cap, predominantly between 75 and 85 degrees MLT in the dawn sector. The events are located broadly spread over the height range 300--600 km. The mean horizontal linear extent of the regions of supersonic flow is estimated to be around 140 km. We find an anticorrelation between Mach number (for 1 < M < 2) and neutral temperature, which may be due to adiabatic cooling of the thermosphere from thermospheric heat sources below the satellite altitude.