Urban dwellers are suffering from more serious thermal discomforts in summer than rural residents. This phenomenon is called Urban Heat Island (UHI). UHI negatively affects residents’ daily life in many aspects, including discomfort, health, and energy consumption. Therefore, exploring UHI mitigation strategies is a universally compelling mission. However, UHI is a complex phenomenon which is affected by a number of factors. To address problems, a profound understanding of UHI is essential. Based on a literature review, researchers have discovered some important strategies for UHI mitigation, including shades, waterbody, and vegetation. In urban areas, these elements are mostly related to parks. The Gold Coast is a coastal subtropical city located on the southeast of Queensland, Australia. There are three key elements that exhibit its urban features: urban forestry parks, the sea, and the hot humid weather. This study aims to explore thermal environments of 18 selected parks around the city to find the thermal performance of each park and its influencing factors. The 18 parks were measured physically by Testo 480 and Winscanopy; the collected data included air temperature, air velocity, relative humidity, sky view factor etc. Design factors of parks, such as tree coverage and surface area, are also measured. Multiple linear regression is used studying the relationships between design factors and thermal performance. It is discovered that trees have more significant effect on park thermal environment adjustment than others, such as park size. Tree coverage is significantly correlated to all thermal indicators (park cooling intensity, mean radiant temperature, and physiological equivalent temperature) while distance to the sea is sensitive to cooling more. The research has important implications for urban planning and management to utilise parks to create better urban thermal environments.