Abstract Empirical equations have been developed which correlate the monthly average daily horizontal diffuse and beam radiation with the fraction of maximum possible number of bright sunshine hours. These correlations are based on measured data from three widely spread Canadian stations. Depending upon whether or not the total horizontal radiation is known, the two correlations for the diffuse radiation are: H d H =0.791−0.635 n N H d H o =0.163+0.478 n N −0.655 n N 2 . The correlation for beam radiation is: H d H o =0.176+1.45 n N −1.12 n N 2 , for n > 0 .