Statistical analysis of new measured sky illuminance data recorded in various climatic zones in Australia has resulted in the determination of regression coefficients which specify typical skylight illuminances in these climatic zones. These illuminances have been compared with calculations using a theoretical model defining average monthly skylight conditions based on relative sunshine duration and turbidity factors in these zones. Results show that skylight availability expressed in terms of sky illuminance on a horizontal plane is closely related to the meteorological climate. From this study it is contended that sky availability in different climatic regions can be determined by relating limited selected periods of measured data to independant variables such as cloud cover and type and solar attitude.