This study was aimed at analyzing the effect of temperature and relative humidity on downlink satellite communication systems over Warri, in Delta State, Nigeria. The data used in this study were temperature, relative humidity and radio signal strength (RSS) obtained from the Nigeria Meteorological Agency (NIMET) for the years 2018 and 2019 respectively, both from January to December. Davis Vantage Vue weather station was used to measure the temperature and relative humidity while Spectrum analyzer was used to measure RSS. Both instruments were set to function simultaneously. Results obtained for all the months shows that the level of radio signal strength under the influence of temperature is higher either RSS ≥ 65% compare to that of relative humidity either RSS ≤ 64% which also fluctuate the level of RSS on daily basis, throughout the years under review. It was realized that there is a variation in the refractive index of the medium through which the radiowaves are propagated, due to the variations in the temperature and relative humidity, these adversely affect the received signals strength over the downlink satellite communication systems. The results obtained from this study will serve as guide for link budget design for satellite communication operators within the study. Therefore, similar study of this kind is recommended in other locations experiencing severe weather conditions.