Abstract: The Shanghai heat wave/health warning system is introduced. The Spatial Synoptic Classification (SSC) is used as the methodology for determination of the air mass classification using the daily meteorological observation data (1989–1998) in the system, and the ten-year-long air mass calendars is established. Through the comparative analysis of the daily air masses and their corresponding mortality, the MT+-pattern air mass is identified as the “offensive” air mass, which is related with the high mortality in heat wave periods in Shanghai. The equation was also produced for the prediction of excessive death by step-wise regression. The system test with actual meteorological data and mortality data in 1999 indicates that the Shanghai Heat/Health warning system has the good capability of warning excessive heat-related deaths .