Protecting cities with AI-driven flash flood forecasting

According to the World Meteorological Organization (WMO), flash floods account for approximately 85% of flood related fatalities worldwide. They typically occur within six hours of heavy rain, turn city streets into gushing rivers, and take more than 5,000 lives annually, making them one of the world’s deadliest disasters. Early warning systems (EWS) are essential for keeping communities safe and informed. They have been proven to save lives and mitigate damage: even a 12-hour lead time can provide a 60% reduction in flash flood damage. However, a stark “warning gap" exists between countries. While the most developed nations benefit from robust forecasting, life-saving infrastructure is largely absent across vast regions of the Global South, where less than half of developing countries have access to multi-hazard EWS. This leaves billions of people without the advance notice that makes a critical difference.

To address this, today we’re announcing the roll-out of Urban Flash Flood forecasts on Flood Hub. By leveraging a new AI-powered methodology, we can now predict the risk of flash floods in urban areas up to 24 hours in advance. These predictions build on years of research and mark a significant breakthrough in our flood forecasting capabilities and an expansion of our flood coverage.

To date, our Flood Forecasting Initiative has focused on riverine floods, where rivers overflow their banks over a relatively slow period. While our forecasts cover over 2 billion people in 150 countries for the most significant riverine floods events, urban flash floods present a unique challenge. Unlike riverine floods, flash floods are characterized by their rapid onset, requiring a fundamentally different forecasting approach.