This article presents the radiometeorological factors contributing to specific fluctuations of signal level in the southwestern part of Nigeria. Earlier in this region, diurnal and seasonal signal level variations in the VHF band were studied in over-the-horizon radiowave propagation (Aboaba 2000). The large variation in the received field strength was correlated with radiometeorological parameters such as atmospheric pressure, temperature and water vapour pressure measured during the period Oct. 1998-Nov. 1998