Shanghai is the biggest and most important industrial and commerical center inChina. Multiple observations show that the urban area is nearly always wanner. Forexample, on Dec. 13, 1979 at 8pm. (a calm dear night) the warmest temperature isotherms (8.5°) were associated with the highest density urban dwellings (fig 2). Some ave-rage records in the coldest temp., annual temp., the number of coldest days and hottestdays all indicated the urban heat effect as shown in table 1-2.The diurnal variation, annual variation and local difference of urban heat islandintensities for Shanghai were shown in fig. 4-5 and table 3-6 as examples.The urban heat island has a number of consequences. During the maximum deve-lopment of an urban heat island, the temperature field often induces a ’’ country breeze’’.There are more thunderstorm days, and heavy rainy days in Shanghai city comparedwith its nearby counties due to the rising current above the heat island. Except themean value of absolute humidity and relative humidity are lower, all the mean tempe-rature value of the coldest month, the hottest month and the annual are higher in urbandistricts compared to the rural areas in average, (table 7-8).