Following the developments in the weather forecasting and computer technologies, the integration of medium-range weather forecasts and flood forecasting has become increasingly widespread. This paper investigates medium-range weather forecasts and flood predictions, analyzing the application of four operational continental-scale flood forecasting systems in Europe, Australia, and the United States, and explores the opportunities and challenges of using medium-range weather forecasts in flood prediction. The paper points out that the opportunities for medium-range weather forecasts include the increasing availability of observational data, advancements in data assimilation techniques, and the application of new technologies such as artificial intelligence and machine learning. However, challenges remain, such as the inherent uncertainty of atmospheric systems, the lack of observational data in some regions, limitations in model accuracy and model scale transformation, and the complexity of ensemble prediction methods. In the future, by overcoming these challenges, medium-range weather forecasts are expected to play a more significant role in improving the accuracy of flood forecasts, providing more effective support for preventing and mitigating flood disasters.