Atmospheric nitrogen (N) deposition and climate change are transforming the way N moves through dryland watersheds. For example, N deposition is increasing N export to streams, which may be exacerbated by changes in the magnitude, timing, and intensity of precipitation (i.e., the precipitation regime). While deposition controls the amount of N entering a watershed, the precipitation regime influences rates of internal cycling; when and where soil N, plant roots, and microbes are hydrologically connected; how quickly plants and microbes assimilate N; and rates of denitrification, runoff, and leaching. We used the ecohydrological model RHESSys to investigate (1) how N dynamics differ between N-limited and N-saturated conditions in a dryland watershed, and (2) how total precipitation and its intra-annual intermittency (i.e., the time between storms in a year), interannual intermittency (i.e., the duration of dry months across multiple years), and interannual variability (i.e., variance in the amount of precipitation among years) modify N dynamics. Streamflow N export was more sensitive to increasing intermittency and variability in N-limited vs. N-saturated model scenarios, particularly when total precipitation was lower—the opposite was true for denitrification. N export and denitrification increased or decreased the most with increasing interannual intermittency compared to other changes in precipitation timing. This suggests that under future climate change, prolonged droughts that are followed by more intense storms may pose a major threat to water quality in dryland watersheds.