GraphCast is a machine learning model that uses graph neural networks to produce global weather forecasts up to ten days ahead at high spatial resolution. The system represents the Earth's surface as an icosahedral mesh, enabling message passing between mesh nodes to capture atmospheric dynamics, and combines this with a learned multiscale processor that operates across coarse-to-fine mesh resolutions.
The model is trained on historical ERA5 reanalysis data through a supervised learning objective, and its autoregressive rollout loop feeds predictions back as input to generate multi-step forecast trajectories while maintaining end-to-end differentiability. GraphCast includes a grid-to-mesh encoder-decoder that converts regular latitude-longitude grid data into the triangular mesh format for processing and decodes outputs back to grid coordinates.
The repository provides three pretrained model snapshots that can generate forecasts without training from scratch, along with a training pipeline for producing custom forecasting models. Conversion utilities are included to transform gridded climate data into the icosahedral mesh representation required by the graph network.