Background and aims Cover crops can increase nitrogen (N) retention in agroecosystems by taking up soil soluble N when the grain crop is absent. We examined how the combination of cover crops and variability in winter conditions can affect soil N retention and N transfer to the subsequent crop.Methods We used N-15 tracer to quantify how the presence of cover crops (both winter-hardy and winter-killed) modifies the recovery by a corn crop of soil soluble N added the previous fall, and we used snow removal to assess how increased freezing would alter N-15 recovery. We predicted snow removal would decrease N-15 recovery in corn, and this decrease would be highest for plots with winter-hardy cover crops, given they remain vulnerable to increased frost over winter.Results We used N-15 tracer to quantify how the presence of cover crops (both winter-hardy and winter-killed) modifies the recovery by a corn crop of soil soluble N added the previous fall, and we used snow removal to assess how increased freezing would alter N-15 recovery. We predicted snow removal would decrease N-15 recovery in corn, and this decrease would be highest for plots with winter-hardy cover crops, given they remain vulnerable to increased frost over winter.Conclusion Although increased soil freezing reduced grain N recovery, cover crops increased soil N retention, which indicates decreased N losses to the surrounding environment, and the potential for increased contributions to grain N in future years.