Aurora 1.5

Aurora 1.5 is Microsoft Weather’s next-generation release of the open Aurora Earth-system foundation model. The model expands Aurora’s original 4 variables to 26, adding 22 new surface, pressure-level, wind, temperature, humidity, precipitation, and radiation fields, and moves to hourly temporal resolution for fine-grained operational guidance. Its headline addition is probabilistic ensemble forecasting, developed through multi-stage fine-tuning that introduces controlled perturbations into the model’s latent conditioning pathway. The model outperforms the ECMWF ensemble on 88.9% of evaluated forecasting targets and improves tropical cyclone track prediction, making it well-suited for energy, agriculture, transportation, and climate-risk applications.

Aurora 1.5 attacks the core problem of putting weather foundation models into real operational use: frontier physics-based systems are trusted but rigid, while earlier open models were hard to adapt, evaluate, and deploy at enterprise scale. The release is tuned for the sectors that depend on integrated Earth-system signals — energy, agriculture, transport, and climate-risk planning — where the distribution of possible outcomes matters as much as a single best estimate.