ABSTRACT Compared to onshore, offshore wind offers a more consistent resource, potential close proximity to load centers, and greater distance from people's view sheds. Much of our understanding of the wind resources in the western north Atlantic derives from remote sensing and scattered measurements. In contrast, offshore wind turbines typically have hub heights exceeding 150 m above sea level. This study uses anemometer data from near hub height obtained from offshore oil and gas exploration and production vessels, combined with well‐established and vetted historical reanalysis data of 10‐m wind heights to develop an observational wind shear model. Although the wind shear magnitudes themselves are in line with other studies of offshore wind, a counterintuitive seasonality is observed. There is more wind shear between 10 m and hub heights during the summer than during the winter. Although this finding seems inconsistent with the physics of atmospheric instability caused by temperature differences between the sea surface and the lower atmosphere, findings at several independent measurement sites in two remote ocean regions of Atlantic Canada are in agreement. This finding may help planning agencies and wind developers to select sites, perform preliminary viability and economic modeling, and thereby facilitate the transition and integration to offshore wind energy.