GEOS Sub-seasonal to Seasonal Prediction system, Version 3

Version 3 of NASA’s GEOS-S2S was released in March, 2026. GEOS-S2S-3 makes extensive use of NASA’s observations, models and assimilation capabilities, and is the first truly seamless prediction system. GEOS-S2S-3 includes a new coupled model, adds assimilation of sea surface salinity to the altimetry used in prior systems, and continues to predict aerosol and aerosol-cloud interactions. The extensive suite of retrospective forecasts allows GMAO to work closely with users to determine the most suitable products for their applications. One new user of these forecasts is the US Seasonal Forecast for Health.