Low- and middle-income countries are more exposed to climate change-related impacts than other countries. In Chile, the northern Atacama Desert is sensitive to changes induced by global warming, especially regarding precipitations. The very low level of annual precipitation experimented by this region makes that cities placed there are totally unprepared to face disruptive events, and climatological predictions show that the frequency of such events will increase, such as the intensity of the precipitations during the event. This chapter analyzes the case of the Antofagasta urban system, evaluating the environmental hazard, the social exposure, and the vulnerability to obtain a global risk evaluation of the system. Two neighborhoods exposed to flooding has been considered and studied by different ways, including climatological simulations, multiple criteria analysis, and interviews to assess risk perception of the inhabitants.