It is important to alleviate the “heat island effect” in urban areas, especially tropical cities. Microclimate is normally affected by the urban morphology parameters. The objective of this work is to investigate the correlation between air temperature variations and urban morphology parameters in tropical cities. Field measurement was carried out to record the air temperature at 27 points within an 8 km² urban area continuously in Singapore for one year. Geographical information system was applied to extract the urban morphology parameters. Generally, the maximum and minimum air temperature spatial differences in the study area ranged from 3.2 to 6.5 °C, indicating the significant effects of urban morphology on the air temperatures. Based on the fitting results of created multilinear regression models, parametric study has been performed to investigate the specific effects of urban morphology parameters on air temperatures. This work has proposed a much more precise regression model to predict the air temperature with various urban morphology parameters. In addition, meaningful value of reference has been offered for urban planners and landscape designers to effectively control the air temperature in tropical cities such as Singapore.