Based on Monthly high temperature data in summer(JJA) from 1961 to 2003 at Nanjing,Hangzhou and Nanchang stations,quite complete time series of severe high temperature are established,and the climatic characteristics and disaster mechanism of high temperature in these areas are analyzed.The observed data in these areas show that oppressive weather lasted for a long time,extreme high temperature was high,daily average wind speed relatively low and daily average humidity higher during the high temperature process.The subtropical high over East Asia is the main climatic system that induced the summer high temperature disaster in these areas.A forecasting model of high temperature days is established using the methods of mean generating function and optimal subset regression.The varification of the 42 years historical records shows that the model can forecast high temperature in these areas successfully.Therefore it can be applied in climate operation.