This paper examines the relationship between climate and the prevalence of malaria in Warri metropolis, Nigeria. Collected climate data was analysed against malaria patient records from three hospitals for a period of twenty years (1990-2009) using a multiple regression approach. The study shows that both rainfall and temperature in Warri metropolis have increased over the past hundred years (1907-2009) by 122.82 mm and 1.3 degrees Celsius. The study highlights the relationship between malaria and climate, and shows that malaria prevalence in Warri metropolis and its environs is significantly dependent on rainfall, relative humidity and temperature. An increase in temperature and relative humidity is likely to increase the number of malaria cases, and the study, therefore, recommends that any policy aimed at reducing the prevalence of malaria must include efforts to reduce the number of mosquitoes through the improvement of the environment, which entails climate change mitigation.