The atmospheric and fuel conditions that led to the case of extreme fire behaviour registered in Puerto Madryn in north-eastern Patagonia, Argentina, on 21 January 1994 were analysed in this study. The analyses included surface and upper-air meteorological conditions, fuel composition and load, and morphometry of the burnt area. When the fire occurred the total fuel load was 16 688 ± 2 611 kg of dry matter per hectare, with fine fuel representing 66% of the total fuel load. At the time of the major fire run, the air temperature reached 32 °C and relative humidity decreased to 13%. The fuel load and its high proportion of fine fuels, the extreme temperatures, the low relative humidity, and the changes in wind directions which resulted from the conjunction of synoptic and local-scale phenomena, enhanced the development of a large convection column which favoured the interaction of surface and upper-air winds. As in similar cases reported for other ecosystems, the combination of these phenomena led to this case of extreme fire behaviour. It is intended that this analysis will contribute to the future development of fire alert systems for the region and to the worldwide knowledge of extreme fire behaviour in different scenarios.