An important application of remote sensing to the study of urban environments is the assessment of surface urban heat islands. Here, we present a review of remotely sensed urban heat islands, how they relate to urban heat islands measured in the atmosphere, and provide guidance on how they may be most appropriately observed using remote sensing. Our paper is illustrated using a detailed case study of the Vancouver BC urban heat island. The study focuses on high resolution thermal imagery obtained from helicopter flights along an urban-rural transect that sample a range of land-uses, land cover and morphometry. Four flights were conducted at times critical in heat island development (mid-afternoon, sunset, midnight and pre-dawn). The mid-afternoon and pre-dawn transects occurred at times of NOAA-11 satellite overpasses. Near-surface air temperature transects using a thermometer on an automobile were also obtained and the surface energy balance was observed at one rural and two urban sites along the route. The spatial and temporal patterns of surface and air temperature are compared and discussed in relation to the definition of the surface being observed. We use the temperature and heat flux observations to assess the applicability of two urban climate models to simulate urban heat islands. One is a relatively simple one-dimensional radiative cooling model (SHIM, Johnson et al. 1991) the other is a more complete, but still one-dimensional, energy balance mode (TEB-ISBA, Masson 2000).