Cooling degree-days (CDD) are a practical method for assessing the effect ambient air temperature has on the energy performance of buildings. In this study, the relationship between midday land surface temperatures derived from NOAA-AVHRR data and mean daily air temperature observations recorded at standard meteorological stations is defined and statistically validated. The relationship is further used for the calculation of CDD. The benefit of this approach is the direct application of daily satellite data for the definition of CDD in urban areas at a spatial resolution of 1.1 km. (c) 2005 Elsevier Ltd. All rights reserved.