Data onfidence, a metric of how "good" a forecast is relative to climatological variability, is plotted for two reanalysis data sets for two different time periods across the Antarctic region.

"One golden observation is worth a thousand simulations."

- from the Ten Extra Commandments for Climate Modeling by J.E. Kutzbach

Welcome to the Climate Data Guide!

The Climate Data Guide (or "Guide") provides concise and reliable information on the strengths and limitations of the key observational data sets, tools and methods used to evaluate Earth system models and to understand the climate system.

The Guide publishes data summaries with access links, intercomparisons, and expert commentaries on the utility of climate data for addressing a wide variety of questions in climate science.

The Guide has helped over a million readers from around the world gain an insider's perspective on data ranging from simple climate indices to state-of-the-art data assimilation products (e.g. reanalysis) to paleoclimate records from tree rings and corals.

Learn More

Dataset categories

View our datasets by the main variables and Earth System components


Atmospheric variables include temperature, precipitation, wind, pressure, clouds, greenhouse gases, and much more. Explore overview pages and a curated list of the most-used data sets, many of them discussed by experts.

Climate Indices

Climate indices are simple diagnostic quantities that are used to characterize an aspect of a geophysical system such as a circulation pattern. Climate Indices track droughts, ENSO events, wind patterns, internal modes of climate variability, and extreme events like wildfires and heatwaves. Climate indices play a key role in climate monitoring and prediction.


Cryospheric variables include sea ice concentration, sea ice thickness, snow cover, permafrost, and more. See a curated list of the most-used data sets, many of them discussed by experts.


Soil moisture, vegetation coverage, surface radiation budgets and more. See a carefully curated list of the most-used data sets, many of them discussed by experts.


Sea surface temperature, salinity, currents, air-sea heat fluxes, sea level, ocean heat content, and more.


Paleoclimate data are derived from Earth's natural climate archives, including tree rings, ice cores, corals, speleothems, and ocean sediments. Such records are used to broaden the sampling of climate variability beyond what is possible from the instrumental record.


Comprehensive weather and climate datasets, reanalyses assimilate a variety of observations of the atmosphere, land surface, and ocean into a forecast model to provide a dynamically consistent estimate of the climate state at each time step.