The effective earth radius factor; k-factor is a major parameter in the prediction of the local radio wave propagation conditions of the lower atmosphere from meteorological variables. In this study the k-factor values were calculated and analyzed from the measurements of air temperature, relative humidity and atmospheric pressure in Auchi area of Edo State, South-South, Nigeria using a self-implemented cost effective portable weather monitoring device for a period of one year; 2017, so as to determine the relationship between these meteorological variables and the k-factor values. The fixed measuring method by placing the weather monitoring device on 188 m height above sea level was employed for the measurements of the various meteorological variables at the administrative block of Edo University Iyamho. The results show that the calculated k-factor values range from 1.06 to 1.94 with an average value of 1.47 and were generally higher during the months with much rainfall compared to that of the months with lesser rainfall. The measured meteorological variables were having significant influences on the calculated k-factor values during all the months, and these influences were more pronounced during the months with much rainfall compared with the months with lesser rainfall. The influence of the air temperature was higher compared to the other meteorological variables. The results that are obtained from this study should be taken into account for enhancement and improvement purposes in radio communication systems.