Urban pluvial flooding is worsening due to climate change and urbanization, requiring faster forecasts. This study presents RIM2D, a multi-graphics processing unit (GPU) 2D flood model, simulating high-resolution events (2–10 m) across Berlin (891.8 km²) with up to 8 GPUs. Simulations of real and synthetic floods show multi-GPU use is vital for fine-scale, timely forecasts. RIM2D proves operationally viable for urban-scale early warning using modern GPU hardware.