To study the cosmic ray modulation properly, it is important to remove atmospheric effects. In this study cosmic ray data from the KACST detector in Riyadh, Saudi Arabia (Rc = 14.4 GV), for the period 2007-2009, were used to study the effect of some meteorological parameters on cosmic ray muons. The parameters of interest are the atmospheric pressure, temperature, and relative humidity. We have found that the atmospheric pressure and temperature are inversely correlated with the muon rate. On the other hand, the relative humidity is correlated with the number of cosmic ray muons.