Monthly mean hourly (MMH) values of direct irradiance are obtained for different locations in Spain corresponding to different climatic conditions. These values are shown through isolines diagrams. Representative values of direct irradiance for different time of the year and different hour of the day can be easily read from these diagrams. Statistical mean values are obtained from hourly direct irradiance experimental data supplied by the National Meteorological Agency in Spain (AEMET) for the period 2002-2012. Simultaneously, a similar analysis is carried out over the clearness index Kt calculated from hourly experimental data of global irradiance. Monthly mean hourly values of Kt are presented by isolines diagrams representing the behavior of this index along the year. Finally, a correlation between MMH values of direct irradiance and clearness index is analyzed.