This study investigated the effect of weather and the days of the week on the number of daily circulations in public libraries. Library circulation data sets were collected from two libraries; one was in an urban area, and the other in a rural ar-ea. After the data was divided by rainy days and other days, holidays and work-days, and each day of the week, the presence or absence of significant differences in the number of circulations per day ware analyzed. Automatic Linear Modeling was performed to analyze how weather, days of the week, and holidays affected the number of daily circulations. The results revealed that days of the week have a large impact on daily circulations in both libraries. However, the weather had a significant impact in urban areas only. Automatic Linear Modeling explained the circulations based on days of the week and holidays with 71.5% accuracy in a ru-ral library and explained the number based on days of the week, holidays, and precipitation amount with 81% accuracy in an urban library.