Microsoft released Aurora 1.5: an open foundation model for weather and Earth systems

Microsoft Research and Microsoft Weather have released Aurora 1.5, a significant extension of the Aurora Earth System foundation model originally introduced in 2024 and published in Nature in 2025. The new version adds 22 additional weather variables relevant to energy, agriculture, transport, and climate risk, increases temporal resolution to hourly, and introduces probabilistic ensemble forecasting. The ensemble version introduces stochastic perturbations to represent model uncertainty, generating multiple forecast members to estimate the spread of possible outcomes. In evaluations, Aurora 1.5's probabilistic forecasts outperform the state-of-the-art ECMWF dynamical ensemble on 88.9% of evaluated targets. For tropical cyclones in 2024–2025, the model reduced track errors by roughly one-third compared to the original Aurora. The model is released as open source on GitHub with model checkpoints on Hugging Face. Microsoft Weather plans to connect the open research with operational services through Microsoft Foundry and Planetary Computer Pro, and partner BKW is already using Aurora 1.5 for energy operations. Other collaborations include Terradot using Aurora-derived representations for carbon dioxide removal estimation and the UK Met Office exploring foundation models alongside physics-based systems.