Open-Meteo

Open-Meteo is an open-source weather API that provides global forecasts and historical weather data. It is designed for use in non-commercial software projects and does not require an API key for access. The software can be used via a hosted API or deployed as a self-hosted server using Docker or prebuilt Ubuntu packages, allowing developers to maintain full control over their weather data infrastructure.

The system processes over 2 TB of data daily from various national weather services, converting complex binary file formats, grid systems, and projections into accessible time-series data. It supports CORS and operates without tracking, cookies, or advertisements. By providing the complete source code, the project allows users to conduct detailed verifications of the weather data processing or implement their own modifications to the API logic.

Key features

• Hourly weather forecasts for up to 16 days
• Global models with 11 km resolution and regional models up to 1.5 km
• Access to 80 years of historical weather data
• Specialized APIs for marine forecasts, air quality, geocoding, elevation, and floods
• Integration of models from NOAA GFS, DWD ICON, ECMWF IFS, and others
• Response times below 10 ms via GeoDNS servers in Europe and North America
• No API key requirement for non-commercial use
• Source code available under the AGPLv3 license

The architecture relies on open-data numerical weather predictions from national services. To optimize access to time-series data, such as 14-day temperature forecasts, the software uses a customized file format and compression technique. The API is utilized by a wide variety of projects, ranging from smart home platforms like Home Assistant and Android weather apps to specialized tools for paragliding pilots and drone operators. It also supports integration with command-line interface tools and embedded systems like Arduino ESP8266 weather stations.

This project serves as a transparent infrastructure for developers who need reliable weather data without the constraints of proprietary API keys or tracking mechanisms.