The prospects outlined in climate scenarios produced for Brazil indicate a probable increase in the number of extreme hydrometeorological events in the coming years. Therefore, a study of the health scourges that may intensify due to these events is important. The scope of this article is to estimate the cost represented by the cases of dengue fever attributed to the 2011 disaster in Nova Friburgo (RJ). There were 1,356 suspected cases of dengue fever, 937 of which were confirmed. The total cost of the disease may have been between R$66,000 and R$499,000 taking the minimum salary as a benchmark, with approximately 70% of this amount being among the confirmed cases. The disaster caused extensive changes in the city's environment which, together with the urban sanitation and clearing up process that occurred in the post-event period, led to an increase in the number of potential mosquito breeding sites, facilitating their proliferation and increasing the number of cases of dengue fever. This was a disease that in the decade prior to the disaster recorded few cases of the disease in the municipality. This illustrates the potential of events like the one that occurred in 2011 in Nova Friburgo may have on the increase in the number of cases, and consequently on the cost of the disease.