Walking is highly encouraged as a sustainable transportation mode. Unlike motorized transportation modes, pedestrians are often exposed to outdoor environments, and hence walking movements are affected by weather conditions. In rainy weather in particular, the use of umbrellas appears to have considerable conflicting effects on crowd movements. Therefore, the influence of rainy weather on pedestrian flow raises concerns regarding the efficiency and safety of the traffic facilities associated with intensive pedestrian movements. This study investigated pedestrian movements at crosswalks under rainy conditions by conducting controlled experiments. The experiments were designed to cover wide ranges of experimental variables, including rainfall intensity, crosswalk width, pedestrian density, total number of pedestrians, umbrella usage proportion, and the split ratio of bidirectional pedestrian flow. Ninety-seven testing scenarios with different variable combinations were adopted in the controlled experiments, and three runs were performed for each scenario. The experiments were video recorded, and pedestrian walking trajectories were extracted for further analysis with the aid of computer programs. The characteristics of bidirectional pedestrian flow under rainy conditions were identified while accounting for proportions of umbrella usage and rainfall intensity, which permitted estimation of the influence of rainy weather on bidirectional pedestrian flows. Fundamental diagrams of the testing scenarios with and without rain are presented to illustrate how pedestrian movements were affected by conflicts between umbrellas and an increase in rainfall intensity. Possible temporary traffic arrangement measures are proposed to alleviate the influence of rainy weather and maintain traffic efficiency at crosswalks and intersections.