This study employs mesoscale simulations using the Weather Research and Forecasting model to investigate wind-farm blockage phenomena over a six-month period in the North Atlantic Ocean. The impact of atmospheric stratification and associated gravity waves on blockage effects is assessed, unencumbered by the presence of nearby land. Simulations reveal the formation of gravity waves at specific times, particularly evident in vertical velocity at hub height. Blockage analysis indicates no significant stratification effects on farm blockage above a Froude number of 10 and increased blockage below a Froude number of 5. Different turbine layouts yield similar results, highlighting the Froude number as a key indicator of gravity wave effects on wind farm aerodynamics. This study underscores the negative impact of stratification effects, driven by gravity waves, on wind farm production, reducing efficiency of additional 3% during approximately 5% of operational time.