This presentation will explore the dynamics of air temperature (screen level) urban heat island evolution in Singapore, a city with a tropical, humid climate. Preliminary results based on observations taken between December 2001 and February 2002 will be presented. Special focus will be on the diurnal cooling and warming rates at an urban and "rural" location, respectively. The data will be analysed within the context of previous heat island studies carried out in Singapore and traverses conducted in spring and summer of 2001 which showed nighttime heat island magnitudes of up to 4 degC with the lowest temperatures observed in densely vegetated (as opposed to open, rural) areas.