Wetlands play important roles regulating the local microclimate. Studying the characteristics of wetland microclimate effects can help to specifically understand the impact of the wetlands on the local microclimate. In this study, we chose Hengshui Lake in Hengshui City, Hebei Province, as the study area and analyzed the microclimate effects of Hengshui Lake during different seasons by comparing the meteorological elements inside and outside the lake. The data came from 11 conventional meteorological stations in Hengshui City. The results show that: (1) Hengshui Lake has a remarkable cold island effect, wet island effect, and a wind island effect, which modify the surrounding climate characteristics. (2) The microclimate effect of Hengshui Lake has an obvious seasonal characteristic. The order of the average cold island effect during the four seasons is spring > winter > autumn > summer; the order of the wet island effect is summer > spring > autumn > winter; and the order of the wind island effect is spring > summer > winter > autumn. The microclimate effect is intense in spring. (3) Hengshui Lake shows an obvious circadian rhythm in its microclimate effect. The cold island effect is stronger at night than during the day, while the wet island and wind island effects are stronger during the day than at night.