Data from a new experimental setup deployed in Dubendorf (Switzerland) are used to quantify and model the magnitude and dynamics of the wet-antenna attenuation (WAA) affecting a 1.85-km commercial microwave link at 38 GHz. The results show that the WAA exhibits the following properties: 1) It is bounded by a maximum value of about 2.3 dB; 2) it increases exponentially toward 2.3 dB during the first 5-20 min of rainfall; and 3) it decreases exponentially as soon as the rain stops. A new dynamic WAA model that reproduces these three features and can be calibrated using solely link measurements is proposed. Its performance is evaluated at different temporal resolutions and compared with other wet-antenna models from the literature. The results show that the dynamic model outperforms all other models and significantly reduces the uncertainty of the retrieved path-averaged rain rates.