Millimeter waves have been recognized as carriers for 5G cellular networks. We carried out a series of millimeter-wave measurements in Beijing, China, and studied the atmospheric impacts on millimeter-wave transmission. Our measurement design is an exemplary LOS transmission link. We also studied a 3 km long commercial E-band millimeter-wave backhaul link in Göteborg, Sweden. We monitored the variation of received signal in the rain, and compared the theoretical rain-induced signal attenuation with the practically monitored signal attenuation. Our results show that there is 1.5-4.5 dB uncertainty between the practical and theoretical rain-induced signal attenuation. Assuming the prediction of rain intensity is available, we have proposed a novel rain-aware radio resource management strategy which adapts the modulation and coding schemes of an OFDM system to rainfall events. We have applied the proposed algorithm to an OFDM - based 5G system, and the throughput result is improved. The result shows that the throughput of a fixed modulation and coding scheme system is between 12%-95% of the system employing the proposed algorithm during rainfall events.