Abstract
The investigation of meteorological effects is of a great importance to the analysis of the cosmic ray variations. In this paper, we study the effect of the ground temperature on the cosmic ray recorded by KACST detector. This detector has monitored secondary cosmic ray muon since 2002 at Riydah, Saudi Arabia; (lat 24 43; long. 46 40; alt. 613 m; Rc similar to 14 GV).