An experiment was carried out in post rainy (rabi) seasons of 2006-07 to 2010-11 for studying the effect of environmental factors and crop phenology on Alternaria leaf spot disease development in safflower under three different sowing conditions viz., early, normal and late at Zonal Agricultural Research Station, Solapur in Maharashtra, India. The studies revealed that subnormal temperature coupled with above normal humidity and rainfall contributed significantly for the disease incidence and its spread under different sowing situations. Safflower plants were susceptible to Alternaria carthami at all growing stages, but susceptibility increased as the plants matured. Further, the percent disease index (PDI) has progressed at linear rate throughout the plant growth and it was negatively correlated with maximum temperature under late sown condition, while it was positively correlated with rainfall, minimum temperature, relative humidity (morning and evening) in addition to age of crop. By employing step down linear regression models, the incidence of Alternaria leaf spot on safflower can be predicted to an extent of 97.6%, 95.3% and 92.2% accuracy under early, normal and late sowing conditions, respectively while with non-linear models the prediction rate for the leaf spot under above sowing situations was improved to 99.8%, 99.6% and 99.4%, respectively.