Monthly average daily data of climatic conditions over the period 1987-1992 in Oman is presented. Regression methods are used to fit polynomial and trigonometric functions to the monthly averages for nine parameters. The parameters, namely atmospheric pressure, vapour pressure, ambient air temperature, relative humidity, sunshine hours, wind speed, evaporation, radiation and rainfall are useful for renewable energy applications. The functions presented for the parameters, excluding rainfall and evaporation, should enable determination of specific parameter values and prediction of missing values. They also provide some insight into the variation of these parameters.