Diarrhea is a significant health problem in Indonesia, particularly in developing regions where the disease is endemic. A substantial number of its cases arise from the contamination of food and water sources. The study focused on West Nusa Tenggara Province, which had a high prevalence rate of diarrhea. It aimed to examine the influence of climate, environmental factors, and regional attributes on diarrhea.The study results can be used to develop region-specific strategies to reduce outbreaks. An ecological method was adopted and data from 10 districts/cities were analyzed. Negative binomial regression was used to evaluate the relationship between monthly diarrhea cases from 2017 to 2020 and climate variables, access to water-sanitation-hygiene (WASH), population density, and well-being indices over the same period. The results showed that rising temperatures increased the number of cases (IRR: 1.095; 95%CI: 1.043-1.149), while relative humidity served as a protective variable. Limited access to drinking water and sanitation increased the risk of diarrhea (IRR: 1,082; 95% IC: 1,056-1,110). Higher temperatures often led to drought, complicating access to safe water sources. Therefore, there was an urgent need for enhanced development of accessible WASH infrastructure, particularly for underserved communities. © The Authors, published by EDP Sciences.