The proportion of global electricity generated by wind is increasing. There are concerns that onshore wind farms may affect local winds and/or patterns, with impacts on local ecosystems. Global-scale evaluations of these impacts are lacking. To investigate this issue, we used TerraClimate and ERA5 datasets covering the years 1980–1999 to judge the impact of onshore wind farms on wind speeds (at 10 m and 100 m elevations) and their distribution patterns. Winds were compared in two periods approximately representing periods without (1980–1999) and with (2001–2020) large-scale wind farms in existence. The TerraClimate dataset shows that 10 m wind speeds decreased at wind farm locations, while the wind speed distribution patterns did not change significantly. However, in the densest wind farm areas, the 10 m wind speeds actually increased. Analysis of the ERA5 data showed no significant changes in 10 m and 100 m wind speeds or distribution patterns at wind farm locations. The influence of wind farms on local and global wind speeds was slight and far less than that of oceanic/atmospheric oscillations. In the long term, the potential for onshore wind farms to reduce global wind speeds or affect their distribution patterns is very small.