During the CAPITOUL field campaign conducted between February 2004 and March 2005, the urban heat island of Toulouse agglomeration was assessed with a 25 measurement stations. At the same time, the surface energy balance was measured at a dense building area of the old core and an inventory of energy consumption by human activities was build at a 100-m resolution. For each of the measurement stations, the morphological parameters of their close environment were evaluated with the city Geographical Information System. From the analyses conducted, the two main following results can be inferred: 1) the spatial structure of the nocturnal heat island does not present significant evolution according to the seasons, 2) during the winter period, there is a good relation between the strongest urban heat island events and the peak of anthropogenic heat releases.