Thermal remote sensing has been widely used to study urban climates, particularly the urban heat island (UHI) effect. This review focuses on the progress made in understanding and quantifying the UHI, addressing methodological questions raised by Roth et al. (1989). While significant progress has been made, the application of thermal remote sensing to urban areas remains limited to qualitative descriptions and simple correlations. The challenge lies in using qualitative land use data to describe urban surfaces rather than more fundamental surface descriptors. Advances in thermal remote sensing for natural and agricultural surfaces offer insights into improving techniques for urban areas. Improvements in satellite resolution, detailed surface representations, and low-cost portable thermal scanners are expected to advance the application of thermal remote sensing in urban climate studies. The review highlights the importance of proper definitions, the nature of urban surfaces as seen by remote sensors, the relationship between sensor-detected temperatures and the true urban-atmosphere interface temperature, and the connection between satellite-derived surface urban heat islands and atmospheric heat islands. It also discusses the suitability of thermal remote sensing data for urban climate models, emphasizing the need for detailed, fully coupled models to predict surface-atmosphere interactions.Thermal remote sensing has been widely used to study urban climates, particularly the urban heat island (UHI) effect. This review focuses on the progress made in understanding and quantifying the UHI, addressing methodological questions raised by Roth et al. (1989). While significant progress has been made, the application of thermal remote sensing to urban areas remains limited to qualitative descriptions and simple correlations. The challenge lies in using qualitative land use data to describe urban surfaces rather than more fundamental surface descriptors. Advances in thermal remote sensing for natural and agricultural surfaces offer insights into improving techniques for urban areas. Improvements in satellite resolution, detailed surface representations, and low-cost portable thermal scanners are expected to advance the application of thermal remote sensing in urban climate studies. The review highlights the importance of proper definitions, the nature of urban surfaces as seen by remote sensors, the relationship between sensor-detected temperatures and the true urban-atmosphere interface temperature, and the connection between satellite-derived surface urban heat islands and atmospheric heat islands. It also discusses the suitability of thermal remote sensing data for urban climate models, emphasizing the need for detailed, fully coupled models to predict surface-atmosphere interactions.