The estimation of rain rate using microwave links has been explored in the past mainly in temperate climates and for frequencies above 5 GHz. This investigation analyses the effectiveness of a variation of the ITU-R P.838 recommendation to estimate rain rate using a 5 GHz radio link in the tropical city of Guayaquil. The measured attenuation due to rainfall over the link was too low to be considered of any practical use, however unexpectedly large values of attenuation were measured when rain was observed at the transmitter site. It was discovered that the cause of this relatively high level of attenuation was the wetting of the antenna; this phenomenon was accurately modeled by a power relationship similar to the one used to estimate attenuation caused by rainfall over a radio link.