<p>While climate and lithology are known to influence rockfall occurrence, their role in producing consistent and transferable seasonal rockfall patterns across different settings remains poorly understood. To document and study variations in seasonal trends, we analyzed results of multi-year high-resolution 3D monitoring at four western Colorado highway slopes (Glenwood Springs (GW), Manitou Springs (MS), Idaho Springs (IS), and Floyd Hill (FH)) that span diverse lithologies and climate regimes. Frequent terrestrial lidar scans (weekly to monthly) and daily photogrammetric surveys recorded hundreds of rockfall events, revealing distinct seasonal patterns at each site. At GW, the event rate peaked in January, and both mean volumetric rate metrics (arithmetic and geometric) peaked in March, all within a late-winter to early-spring window. In contrast, rockfall at MS, IS, and FH was most frequent in spring and summer, associated with high total liquid input. Although peak rockfall months differ among sites as driven by contrasts in snowmelt versus rainfall dominance, the timing of elevated activity at each site consistently tracked its seasonal peak in liquid water input. This result suggests that the seasonal timing of liquid water input has a consistent influence on the seasonality of rockfall hazard, though the degree to which this relationship transfers to other settings, particularly those where freeze–thaw cycling operates as a substantial rockfall trigger, warrants further investigation.</p>