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Here we present a first look at the Gross Primary Production (GPP) forecast skill levels achievable with a state‐of‐the‐art subseasonal‐to‐seasonal (S2S) forecast system. Using NASA's retrospective S2S ensemble forecast in conjunction with a terrestrial biosphere model, and using an independent, remote sensing‐based data set for validation, we demonstrate an ability to accurately forecast spring‐summer carbon uptake at multi‐month leads. Averaged across mid‐ and high latitudes of the Northern Hemisphere land, the GPP forecast initialized on January 1 produces statistically significant skill through summer. The skill achieved, however, is spatially variable, with some regions appearing to extract skill from accurate forecasts of snowpack removal and others extracting skill from the initialization of carbon and nitrogen states. Our results reveal some heretofore unexplored facets of climate predictability and provide a look at what might be possible with future S2S forecast systems that are fully integrated with biogeochemical cycles. Plain Language Summary: Seasonal forecasts of meteorology can support a variety of applications that can help manage precious natural resources. As an integral part of the Earth system, the land ecosystem plays an important role in seasonal forecasts; however, our ability to predict variations in the land's carbon cycle, which is tied strongly to the land's water and energy cycles, is not well understood. This study is a first look at the ability of a state‐of‐the‐art seasonal forecast system to predict year‐to‐year variations in the land's carbon uptake. We demonstrate that the system can accurately forecast spring‐summer carbon uptake several months ahead of time across many mid‐ and high latitude land areas within the Northern Hemisphere. This skill appears to be related both to accurate forecasts of snow removal timing and to the proper specification of land carbon and nitrogen conditions at the beginning of the forecasts. The consideration of carbon and nitrogen dynamics will undoubtedly be standard someday in seasonal forecast systems; this study provide a glimpse at what we might expect from such enhancements. Key Points: We demonstrate skillful forecasts of land carbon uptake in mid‐ to high latitudes at multi‐month leads (winter into summer)During spring, Gross Primary Production (GPP) forecast skill in some regions appears to stem from skillful forecasts of snow removal dateIn certain other regions, initialization of the carbon and nitrogen reservoirs appears to contribute to GPP forecast skill [ABSTRACT FROM AUTHOR]