The New Zealand Government has a goal of a 100% renewable electricity system by 2035. Wind generation is expected to play a major role in achieving this target. However, there is limited public data on current and potential wind generation. We use the Renewables.ninja model to simulate wind output at 44 wind farm sites in New Zealand over a 20-year period. We make our data publicly available and use them to analyse New Zealand & rsquo;s wind resources. We find the long-run average capacity factors over all current and potential sites is 40%. It is lowest in autumn (around 35%) and highest in spring (around 45%). Output is similar across all demand percentiles with little correlation between wind output and demand. A small positive correlation exists between wind output and daily inflows into hydro storage dams. A more significant positive correlation exists between wind output and inflows in the period leading up to winter (when lake levels are typically lowest), implying that wind cannot help energy shortfall during dry years. Finally, we explore how much wind capacity must be installed to give a 100% renewable electricity system, and the trade-offs between energy storage and spilling wind for achieving this target. (c) 2021 Elsevier Ltd. All rights reserved.