Since the 1990's London, UK has experienced a number of noteworthy heat events. Most dramatic of these was the August 2003 event resulting in 600 extra deaths over a 10-day period. This paper will investigate the spatial and temporal patterns of mortality and ambulance call-outs and assess the association between them for a number of heat events in London. The spatial patterns of mortality and call-out will also be compared with a theoretical index of heat sensitivity in order to establish whether, based on a priori assumptions about the associated between heat mortality and morbidity, the spatial pattern of heat health outcomes can be predicted for extreme heat episodes.