Population vulnerability assessment is the analysis of the expected impacts, modeling hazard, exposure, sensitivity and the lack of adaptive capacity of a region or sector to the effects of intense climate or weather extreme events. Vulnerability estimation encompasses more than simple measurement of the potential harm caused by extreme events. The term vulnerability is used differently in the climate change context. The Glossary of the Intergovernmental Panel of Climate Change - the IPCC Fifth Assessment Report defines vulnerability to climate change broadly as follows: "The propensity or predisposition to be adversely affected. Vulnerability encompasses a variety of concepts including sensitivity or susceptibility to harm and lack of capacity to cope and adapt". It is noted explicitly "Reflecting progress in science, this glossary entry differs in breadth and focus from the entry used in the Fourth Assessment Report and other IPCC reports". In this paper one presents a conceptual probability-based climate-driven model for population vulnerability and one illustrates the model taking into account a Brazilian vulnerable region.