Acoustic signals received in the northeast coastal regions of the United States from rockets launched at Cape Kennedy show strong seasonal effects. For the Saturn V rockets, strong signals are received in winter, very weak signals in summer, and weak signals in the transitional months of early fall and spring. These seasonal effects are attributed to the winds in the stratosphere (around an altitude of 50 km). In winter, when strong signals are received, the stratospheric winds have strong components in the direction of propagation of the signals. These components are weak during the transitional months, and during summer the stratospheric winds have components in the direction opposite to that of the signal propagation. It is shown that calculations of horizontal trace velocities provide an indirect method of estimating upper atmospheric winds.