Hail is one of the important weather disasters that affects the Beijing-Tianjin (BT) region.To better understand and to improve the forecasting of hail events over the BT region,the precursor weather conditions for hail based on 30 previous hail events were derived.It was found that the high-level trough and low-level cold front over the Mongolian region,the accumulated convective available potential energy,the decrease of the height of the 0°C-isotherm in the morning,and the persistence and intensification of these factors from morning to afternoon are valuable clues for forecasting the occurrence of hail events over the BT region.