Diarrheal disease has long been known to be a burden to children worldwide. Although child mortality rates as a result of diarrhea have decreased over the past two decades, overall diarrhea incidence has remained relatively stable. In Cambodia, diarrhea was the third most prevalent outpatient diagnosis for children under five in 2012, with a reported incidence rate of 12 per 100 children, up from 7 per 100 children in 2008 (Ministry of Planning Cambodia, 2012). Cambodia is an agricultural country with 80% of the population living in rural areas (National Institute of Statistics Ministry of Planning, 2013). Many are also poor, with 20.5% of the population living at or below the poverty line (Sobrado et al., 2014). As a result, a large portion of the population is vulnerable to changing climate patterns and seasonal rainfalls. These patterns have been shown to have an effect on the incidence of diarrhea in regions throughout the world. This research evaluated the relationship between seasonality and the incidence of diarrheal disease in children under five years old in the Rumduol district, Svay Rieng province of Cambodia. Using monthly under-five diarrhea data from a local health center and meteorological data from the Ministry of Water Resources and Meteorology (MoWRAM), Spearman’s Correlation was used to find associations between monthly rainfall, heavy rainfall (defined by the 90th percentile), maximum average monthly temperature, and minimum average monthly temperature. Additionally, household surveys, interviews, and observations were used to understand how seasonal behavior, age/gender, household practices, and caregiver perception of the disease affect decisions surrounding diagnosis and treatment of childhood diarrhea throughout the year. Based on the results of the analysis, the number of heavy rainfall days had a weak negative association with monthly under-five diarrhea incidence in the initial month and following month, referred to as lag 0 and lag 1 (rs(96) = -.216, p = .035 and rs(95) = -.219, p = .033). Minimum average monthly temperature was also shown to have weak negative association with monthly under-five diarrhea incidence at lag 0 and lag 1 (rs(96) = -.208, p = .042 and rs(95) = -.212, p = .039). The negative correlation between heavy rainfall and under-five diarrhea indicates that heavy rain can have a washing effect on the environment at lag 0 and lag 1 months. Higher diarrhea incidence in the cooler months suggest a possible link to rotavirus, however more research must be done to make confirm this. Monthly rainfall was seen to have a positive association with diarrhea within the lag 3 and lag 4 months (rs(93) = .250, p = .015; rs(92) = .222, p = .034). This indicates that increased rainfall could have a delayed effect on diarrhea by three or four months. Maximum temperature did not have statistically significant results. These results show that heavy rainfall and minimum temperature likely play role in under-five child diarrhea in the study area at shorter lags times, while monthly rainfall has a greater effect at longer lag times. Results of survey and interview data showed participants had sufficient knowledge on personal and food hygiene practices but often practiced improper environmental hygiene behavior, especially as it related to the handling of child and animal feces. Additionally, there were statistically significant results when looking at the relationship between environmental hygiene knowledge and practice and households where mothers migrate for work. Households with migrant mothers was common within the study area, with 51.9% of households having a mother who was currently working away from home or had plans to return to work soon. More data is needed to further investigate this relationship; however, this result suggests that hygiene knowledge and practice could suffer in households where the mother is absent, as added burden is placed on grandmothers to do domestic and childcare work.