Downward Longwave Radiation (DLR) plays a crucial role in sustaining the temperature of the Earth’s surface and is vital for maintaining the planet’s energy equilibrium. In this study, eight different emissivity equations were utilized to estimate DLR models and to investigate which is more suitable for evaluating DLR in Ikeja, when statistically tested using five validation indices of Mean Bias Error (MBE), Root Mean Square Error (RMSE), Mean Percentage Error (MPE), t-statistic and Index of Agreement (IA). The impact of some meteorological parameters on DLR was investigated. The data used were obtained from the National Aeronautics and Space Administration (NASA) for a period of 39 years (1984 to 2022), the meteorological parameters are monthly average temperature, relative humidity (RH), DLR and Global Solar Radiation (GSR). Findings indicated that Ikeja recorded its highest value of DLR in April with 425.6915 Wm-2, and its lowest value was in January with 406.2774 Wm-2. The Kruk et al. model was found more accurate for evaluating DLR in Ikeja, indicating that in the absence of measured DLR data, Kruk et al. model is highly recommended for estimating DLR in Ikeja. As the temperature is low during the rainy season, the DLR is high and as the temperature is high during the dry season, the DLR is low. The DLR and RH are high during the rainy season and low during the dry season. The average DLR and GSR values obtained were found to be 418.1707 Wm-2 and 195.5164 Wm-2 respectively, this indicate that the DLR values are twice as much as the GSR during the period under investigation.