Based on the daily maximum temperature of midsummer (June to August) from 1950 to 2005, T213 grid wind data, and vertical velocity from June to August in the year of 2002 and 2003 in Wuhan, the climatic characteristics of midsummer high temperature, high mperature processes and characteristics of the western Pacific subtropical high activities are studied. The analysis results show that: there were five high temperature periods with the number of high temperature days being greater than normal: the late 1950s to early 1960s, the middle 1960s, the late 1970s, and the 1990s to the early and mid 2000s. The number of high temperature days was less than normal in the 1980s. To larger time scale, the hightemperature weather occurred in the periods from the late 1950s to 1960s and the late 1990s to the early 2000s. The severe high temperature processes occurred usually on the period from late July to the early August. The western Pacific Subtropical High was the main influencing weather system for high temperature and severe high temperature processes, which controlled the middle and lower reaches of the Yangtze River steadily. With the data of temperature prediction products and zonal winds from ECMWF and T213 products, a method of gray forecasting is proposed to build a forecast model of midsummer high temperature for Wuhan. The model was put to test in the midsummers of 2003 and 2006, and it is proved that it has a certain reference value in quantitative forecasting of high temperature.