Diarrhea is the second leading cause of death in children under five year and is considered a prevailing problem in many developing countries, including in Indonesia. Diarrhea is a multifactorial disease and season is suggested as one of the attributing factors of this disease. This study aimed to identify the association between the rainy season and diarrhea in 13- to 24-month-old toddlers. This was a cross-sectional analytical observational study on medical records of 13- to 24-month-old-toddlers with infectious diarrhea who visited Penjaringan I Sub-district Public Health Center, North Jakarta, Indonesia from 2016 to 2019 that included three cycles of the rainy and dry seasons. Data collection was performed in March 2020 and 286 medical records were included in the study. The relationship between the independent and dependent variables was analyzed using chi-square. Of the total cases, 83 cases occurred in rainy season and 203 cases occurred in dry season (p=0.291). Diarrhea was seen in girls aged13–16 months. There is no significant association between rainy season and diarrhea.