In this study, observations and aerial surveys were conducted in delineating the heat island patterns. Concurrent datasets from the satellite-borne MODIS sensor and helicopter-borne thermal IR imager were employed. The sampling data in this experiment covered an area exceeding 100 km2 in Taiwan's western plain. A more than 10°C temperature difference between different sampling points could be observed in this area. The relationship between the surface temperature and vegetation index values was also showed. Results showed that the surface canopy and the air humidity together played an important role in the surface temperature increase.