GenCast

GenCast, released in late 2024, was the moment AI weather forecasting stopped being a curiosity. It was the first probabilistic model, meaning one that gives you a spread of possible outcomes rather than a single answer, to outperform the European ensemble forecast that professional meteorologists rely on. DeepMind published it openly.

Technically it works like an image generator, using diffusion to refine a noisy guess of the atmosphere into a forecast. That is accurate but slow, since each forecast step needs dozens of passes through the network. Its successor WeatherNext Cyclones swapped the approach for a faster method that needs only one pass, making it roughly eight times quicker and freeing up compute to run far more scenarios per storm.