Studies on microwave signal propagation provide an opportunity to investigate the variable nature of the atmosphere. The present study deals with the effect of sea breeze on the propagation characteristics observed over a line-of-sight (LOS) microwave link operating at 6 GHz and situated in the south-east coast of India. It has been found that the amplitude of the received microwave signal suffers appreciably during the onset of sea breeze. The correlation between the cases of onset of sea breeze observed from microwave amplitude measurements and those from meteorological observations has been found to be good. The large change in refractivity has been observed during the onset of sea breeze. Such change in refractivity profile causes fading in microwave radio signals.