Microsoft's Aurora 1.5 AI Model Goes Open Source With Smarter Weather Forecasting

Microsoft has quietly dropped one of its biggest AI announcements of the year, and this one isn’t about Copilot or Windows. Instead, the company has unveiled Aurora 1.5, the latest version of its AI-powered weather foundation model, bringing broader forecasting capabilities, open-source availability, and enterprise-ready improvements. The update was announced through the Microsoft Research Blog and marks the next major step for Microsoft’s AI weather ambitions.

Microsoft expands Aurora with hourly forecasts and open-source access

Unlike the original Aurora model, Aurora 1.5 dramatically expands what the AI can predict. Microsoft says the new release adds 22 additional weather variables, increasing coverage from just four variables previously. These include temperature, humidity, wind, precipitation, radiation, and several atmospheric measurements that are useful across industries such as agriculture, transportation, energy, and climate planning.

Another major addition is hourly forecasting. Previous versions focused on broader forecast windows, but Aurora 1.5 now delivers much finer time resolution, allowing organizations to better predict events such as heavy rainfall, cloud cover, or tropical cyclone landfalls.

Microsoft is also introducing ensemble forecasting, one of the most requested features from researchers. Instead of generating a single prediction, Aurora 1.5 produces multiple forecast scenarios to estimate uncertainty and improve confidence when planning around severe weather. According to Microsoft, Aurora 1.5 outperformed the ECMWF ensemble system across 88.9% of evaluated forecast targets during internal testing.

The company has also made Aurora 1.5 open source, publishing the model on GitHub alongside checkpoints on Hugging Face. Microsoft says researchers and developers can freely evaluate, fine-tune, and extend the model for their own projects.

In addition to research, Microsoft plans to integrate Aurora 1.5 more deeply into Microsoft Weather services, Azure AI Foundry, and Planetary Computer Pro. The company also highlighted collaborations with organizations including the UK Met Office and climate startup Terradot to explore real-world forecasting and climate applications.

While Aurora 1.5 is aimed primarily at researchers and enterprise customers, the release signals Microsoft’s growing investment in AI-powered weather forecasting, an area the company says already powers weather experiences across Windows, Bing, Edge, Copilot, and MSN, reaching more than a billion devices worldwide. According to Microsoft, the model is designed to complement traditional physics-based forecasting systems rather than replace them.

In related Microsoft news, the company is expanding its AI-driven Windows security strategy while warning that delaying Windows updates is becoming increasingly dangerous as AI helps attackers identify and exploit vulnerabilities more quickly.