Outdoor thermal comfort (OTC) studies explore outdoor subjects’ responses to their thermal environment, usually evaluated using the neutral temperature (NT). This study investigated the influences of microenvironmental factors around a waterbody on thermal perceptions, using questionnaires and meteorological measurements at the Central Lake of Southwest University of Science and Technology (SWUST) in Mianyang. Microenvironmental factors included sky view factor (SVF) and distance from the lake (DFL). It was found that people felt most comfortable in the shade of trees although some volunteers voted artificial canopy as their preferred thermal adaptation element. In addition, a linear regression yielded an NT of 28.44 °C in Mianyang during the summer of 2022. There were NT variations among different measurement sites (e.g., on the east shore, it was 28.18 °C on the waterside, 27.11 °C away from the lake, and 25.53 °C far from the lake; while it was 27.57 °C under the tree crown, 25.11 °C on the lawn, and 29.13 °C in the square). This variation may be due to human adaptation towards microenvironmental factors and their effects on microclimate. The variation in thermal responses owing to microenvironmental differences (different NTs at various types of sites) might be a novel finding in the field of OTC. This study provides important directions for microenvironment design in the future for OTC improvement.