Satellite imagery, weather records, and environmental monitoring data. Large, well-structured, and mostly public domain.
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Climate and earth observation data covers the physical planet: satellite imagery, weather records, ocean and atmosphere measurements, and long environmental time series. It is large, well-structured, and mostly public domain, because much of it comes from government agencies whose remit is to publish. For a RAG system, the setup that answers questions by retrieving relevant material and then generating a reply from it, the value is usually in the descriptive and tabular layers rather than the raw imagery: dataset documentation, station records, and the summary indicators built on top of the measurements.
Choosing within this category means being honest about what you are building. If you want a system that answers questions in words, sources like the World Resources Institute, which publish analysis and indicators, retrieve far better than a satellite archive full of pixels. If you genuinely need the underlying observations, providers like Copernicus, NASA Earthdata, and NOAA give you enormous, authoritative archives, but you will do real engineering to turn them into passages worth retrieving. Weather providers such as the Met Office sit in between, with both bulk data and readable forecasts and reports.
Two things to watch. First, formats: a lot of this data arrives in scientific containers like NetCDF or GeoTIFF that are not text at all, so plan a conversion step before you can embed it, the process of turning text into searchable numerical vectors. Second, access: several archives are free but need registration or an API key, and some throttle heavy downloads. The sources below run from ready-to-read environmental analysis through to the raw observation archives underneath it.
The EU's flagship Earth observation programme. The Copernicus Climate Change Service portal provides authoritative information about past, present, and future global climate, derived from Sentinel reference products alongside other satellite observations and in-situ measurements.
The Centre for Environmental Data Analysis hosts UK atmospheric and Earth observation data, including Met Office archives, climate model outputs, and satellite data.
The home for full and open access to NASA's Earth science data collections. The umbrella portal for the largest collection of freely available Earth science data in the world, with over 12,400 datasets spanning land, ocean, atmosphere, and cryosphere, collected by satellite missions, airborne campaigns, and ground stations.
Free, full, and open access to NOAA data through partner platforms including Amazon Web Services, Google, and Microsoft Azure. Covers climate data records and atmospheric, oceanic, and terrestrial datasets from one of the largest climate archives in the world.
Google Research's open benchmark and curated ERA5-derived data archive for evaluating data-driven global weather models over the one-to-fifteen-day range. It bundles an Apache-licensed evaluation framework, cloud-hosted ground-truth and baseline forecast datasets in Zarr, and a continuously updated leaderboard ranking models such as GraphCast and Pangu-Weather against ECMWF's IFS.
Free environmental data for GIS, climate research, and sustainability projects. Includes Global Forest Watch and other environmental monitoring datasets.