The observation was carried out in Nagahama-city, Shiga-prefecture for two days in the end of July, 1996. Starting from the shore of a lake, in the section of about 3800m to an edge of urban district, we set a self-registering thermometer at nine points along the prefectual road that was vertical to the shore of a lake, and air temperatures were continuously measured in the urban canopy layer. Also, we set six self-registering thermometers in the tower of NTT at the center of city and vertical air temperatures were continuously measured in the lower urban boundary layer. Anemometers were set on the tower of NTT, Nagahama City Hall and the park in the shore of a lake. Amounts of global solar radiation and atmospheric radiation were measured at Nagahama City Hall. During observation period, weather was almost clear. From cross-sectional figures of air temperature, heat island was formed in the center of Nagahama-city. The daily maximum temperature became about 16: 00J.S.T. from diurnal variations of air temperature in Nagahama-city. Lake breeze blew from about 9: 00J.S.T. to about 17: 00J.S.T., and air temperature in the urban canopy layer was calm, but it was mitigated by lake breeze.