"The Restoring Construction of the Cheonggye Stream", that is a huge construction project through which the stream covered with roads will be readjusted with the pro-environmental area from west to east across the metropolitan area in Seoul, has been in progress since June 19 of 2003. Much interest from various fields has been concentrated on the changes that have occurred after the construction. In a meteorological perspective, an evaporative cooling caused by a change of land-use type from roads to water streams and green fields from the restoring project contributes to the mitigation of an urban heat island which mainly affects the local atmospheric circulation, air pollution transport, and human activities in metropolis. The cooling effect as can be approximated quantitatively from the free-water pan evaporation (Ep) measured by a class A type pan. For this purpose, an automated weather monitoring system has been operated near the construction area since July 2003. Preliminary results needed to estimate the evaporative cooling effect and annual variation of Ep at the station are suggested in this experiment.